Hi Waghmare,

Use below code.

Add another TemplateField in the GridView to display Edit and Delete Button.

Check this example. Now please take its reference and correct your code.

Database

I have made use of the following table Customers with the schema as follows.

I have already inserted few records in the table.

You can download the database table SQL by clicking the download link below.

Download SQL file

HTML 

<asp:ScriptManager ID="ScriptManager1" runat="server" />
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
    <ContentTemplate>
        <asp:GridView ID="gvCustomers" runat="server" AutoGenerateColumns="false" class="table table-striped"
            ClientIDMode="Static">
            <Columns>
                <asp:BoundField DataField="CustomerId" HeaderText="ID" />
                <asp:BoundField DataField="Name" HeaderText="Name" />
                <asp:BoundField DataField="Country" HeaderText="Country" />
                <asp:TemplateField HeaderText="Action">
                    <ItemTemplate>
                        <asp:Button ID="btnEdit" Text="Edit" runat="server" OnClick="Edit" CssClass="btn btn-primary" />
                        <asp:Button ID="btnDelete" Text="Delete" runat="server" CssClass="btn btn-danger"
                            OnClick="Delete" OnClientClick="return confirm('Are you sure you want to delete?')" />
                    </ItemTemplate>
                </asp:TemplateField>
            </Columns>
        </asp:GridView>
        <hr />
        <table align="center">
            <tr>
                <td>Id</td>
                <td><asp:Label ID="lblId" runat="server" CssClass="form-control" /></td>
            </tr>
            <tr>
                <td>Name</td>
                <td><asp:TextBox ID="txtName" runat="server" CssClass="form-control" /></td>
            </tr>
            <tr>
                <td>Country</td>
                <td><asp:TextBox ID="txtCountry" runat="server" CssClass="form-control" /></td>
            </tr>
            <tr>
                <td colspan="2" align="center">
                    <asp:Button ID="btnSave" Text="Save" runat="server" OnClick="Save" CssClass="btn btn-success" />
                </td>
            </tr>
        </table>
    </ContentTemplate>
</asp:UpdatePanel>
<link type="text/css" rel="stylesheet" href="https://cdn.datatables.net/1.10.9/css/dataTables.bootstrap.min.css" />
<link type="text/css" rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css" />
<link type="text/css" rel="stylesheet" href="https://cdn.datatables.net/responsive/1.0.7/css/responsive.bootstrap.min.css" />
<link type="text/css" rel="stylesheet" href="https://cdn.datatables.net/buttons/1.2.2/css/buttons.dataTables.min.css" />
<script type="text/javascript" src="https://code.jquery.com/jquery-1.12.4.js"></script>
<script type="text/javascript" src="https://cdn.datatables.net/1.10.9/js/jquery.dataTables.min.js"></script>
<script type="text/javascript" src="https://cdn.datatables.net/responsive/1.0.7/js/dataTables.responsive.min.js"></script>
<script type="text/javascript" src="https://cdn.datatables.net/1.10.9/js/dataTables.bootstrap.min.js"></script>
<script type="text/javascript" src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/js/bootstrap.min.js"></script>
<script type="text/javascript" src="https://cdn.datatables.net/buttons/1.2.2/js/dataTables.buttons.min.js"></script>
<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/jszip/2.5.0/jszip.min.js"></script>
<script type="text/javascript" src="https://cdn.rawgit.com/bpampuch/pdfmake/0.1.18/build/pdfmake.min.js"></script>
<script type="text/javascript" src="https://cdn.rawgit.com/bpampuch/pdfmake/0.1.18/build/vfs_fonts.js"></script>
<script type="text/javascript" src="https://cdn.datatables.net/buttons/1.2.2/js/buttons.html5.min.js"></script>
<script type="text/javascript">
    $(function () {
        $('[id*=gvCustomers]').prepend($("<thead></thead>").append($(this).find("tr:first"))).DataTable({
            "responsive": true,
            "sPaginationType": "full_numbers",
            "bPaginate": true,
            "bSort": true,
            "aLengthMenu": [[10, 25, 50, 75, 100, 500, -1], [10, 25, 50, 75, 100, 500, "All"]],
            "iDisplayLength": 10,
            "stateSave": true,
            "stateDuration": 60 * 1,
            "order": [[1, "asc"]],
            "dom": 'Bfrtip',
            "aoColumnDefs": [{ 'bSortable': false, 'aTargets': [0]}],
            "iDisplayLength": 2,
            buttons: [
                { extend: 'copy', text: 'Copy', exportOptions: { columns: 'th:not(:last-child)', modifier: { page: 'all'}} },
                { extend: 'excel', text: 'Excel', filename: 'Customers_Excel', exportOptions: { columns: 'th:not(:last-child)', modifier: { page: 'all'}} },
                { extend: 'csv', text: 'CSV', filename: 'Customers_Csv', exportOptions: { columns: 'th:not(:last-child)', modifier: { page: 'all'}} },
                { extend: 'pdf', text: 'PDF', filename: 'Customers_Pdf', orientation: 'landscape', pageSize: 'LEGAL', exportOptions: { modifier: { page: 'all' }, columns: ':visible'}}]
        });
    });
    //On UpdatePanel Refresh.
    var prm = Sys.WebForms.PageRequestManager.getInstance();
    if (prm != null) {
        prm.add_endRequest(function (sender, e) {
            if (sender._postBackSettings.panelsToUpdate != null) {
                $('[id*=gvCustomers]').prepend($("<thead></thead>").append($('[id*=gvCustomers]').find("tr:first"))).DataTable({
                    "responsive": true,
                    "sPaginationType": "full_numbers",
                    "bPaginate": true,
                    "bSort": true,
                    "aLengthMenu": [[10, 25, 50, 75, 100, 500, -1], [10, 25, 50, 75, 100, 500, "All"]],
                    "iDisplayLength": 10,
                    "stateSave": true,
                    "stateDuration": 60 * 1,
                    "order": [[1, "asc"]],
                    "dom": 'Bfrtip',
                    "aoColumnDefs": [{ 'bSortable': false, 'aTargets': [0]}],
                    "iDisplayLength": 2,
                    buttons: [
                        { extend: 'copy', text: 'Copy', exportOptions: { modifier: { page: 'all'}} },
                        { extend: 'excel', text: 'Excel', filename: 'Customers_Excel', exportOptions: { columns: 'th:not(:last-child)', modifier: { page: 'all'}} },
                        { extend: 'csv', text: 'CSV', filename: 'Customers_Csv', exportOptions: { modifier: { page: 'all'}} },
                        { extend: 'pdf', text: 'PDF', filename: 'Customers_Pdf', orientation: 'landscape', pageSize: 'LEGAL', exportOptions: { modifier: { page: 'all' }, columns: ':visible'}}]
                });
            }
        });
    };
</script>

Namespaces

C#

using System.Data.SqlClient;
using System.Configuration;
using System.Data;

VB.Net

Imports System.Data.SqlClient
Imports System.Data

Code

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!this.IsPostBack)
    {
        BindGridView();
    }
}

private void BindGridView()
{
    string constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
    using (SqlConnection con = new SqlConnection(constr))
    {
        using (SqlCommand cmd = new SqlCommand("SELECT CustomerId,Name,Country FROM Customers", con))
        {
            using (SqlDataAdapter sda = new SqlDataAdapter(cmd))
            {
                cmd.CommandType = CommandType.Text;
                DataTable dt = new DataTable();
                sda.Fill(dt);
                gvCustomers.DataSource = dt;
                gvCustomers.DataBind();
            }
        }
    }
}

protected void Edit(object sender, EventArgs e)
{
    GridViewRow row = (sender as Button).NamingContainer as GridViewRow;
    lblId.Text = row.Cells[0].Text.Trim();
    txtName.Text = row.Cells[1].Text.Trim();
    txtCountry.Text = row.Cells[2].Text.Trim();
}

protected void Delete(object sender, EventArgs e)
{
    GridViewRow row = (sender as Button).NamingContainer as GridViewRow;
    string customerId = row.Cells[0].Text.Trim();
    string constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
    using (SqlConnection con = new SqlConnection(constr))
    {
        using (SqlCommand cmd = new SqlCommand("Delete From Customers WHERE CustomerId = @Id", con))
        {
            cmd.CommandType = CommandType.Text;
            cmd.Parameters.AddWithValue("@Id", customerId);
            con.Open();
            cmd.ExecuteNonQuery();
            con.Close();
        }
    }

    BindGridView();
}

protected void Save(object sender, EventArgs e)
{
    string constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
    using (SqlConnection con = new SqlConnection(constr))
    {
        using (SqlCommand cmd = new SqlCommand("UPDATE Customers SET Name = @Name,Country = @Country WHERE CustomerId = @Id", con))
        {
            cmd.CommandType = CommandType.Text;
            cmd.Parameters.AddWithValue("@Id", lblId.Text.Trim());
            cmd.Parameters.AddWithValue("@Name", txtName.Text.Trim());
            cmd.Parameters.AddWithValue("@Country", txtCountry.Text.Trim());
            con.Open();
            cmd.ExecuteNonQuery();
            con.Close();
        }
    }

    lblId.Text = string.Empty;
    txtName.Text = string.Empty;
    txtCountry.Text = string.Empty;

    BindGridView();
}

VB.Net

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
    If Not Me.IsPostBack Then
        BindGridView()
    End If
End Sub

Private Sub BindGridView()
    Dim constr As String = ConfigurationManager.ConnectionStrings("constr").ConnectionString
    Using con As SqlConnection = New SqlConnection(constr)
        Using cmd As SqlCommand = New SqlCommand("SELECT CustomerId,Name,Country FROM Customers", con)
            Using sda As SqlDataAdapter = New SqlDataAdapter(cmd)
                cmd.CommandType = CommandType.Text
                Dim dt As DataTable = New DataTable()
                sda.Fill(dt)
                gvCustomers.DataSource = dt
                gvCustomers.DataBind()
            End Using
        End Using
    End Using
End Sub

Protected Sub Edit(ByVal sender As Object, ByVal e As EventArgs)
    Dim row As GridViewRow = TryCast((TryCast(sender, Button)).NamingContainer, GridViewRow)
    lblId.Text = row.Cells(0).Text.Trim()
    txtName.Text = row.Cells(1).Text.Trim()
    txtCountry.Text = row.Cells(2).Text.Trim()
End Sub

Protected Sub Delete(ByVal sender As Object, ByVal e As EventArgs)
    Dim row As GridViewRow = TryCast((TryCast(sender, Button)).NamingContainer, GridViewRow)
    Dim customerId As String = row.Cells(0).Text.Trim()
    Dim constr As String = ConfigurationManager.ConnectionStrings("constr").ConnectionString
    Using con As SqlConnection = New SqlConnection(constr)
        Using cmd As SqlCommand = New SqlCommand("Delete From Customers WHERE CustomerId = @Id", con)
            cmd.CommandType = CommandType.Text
            cmd.Parameters.AddWithValue("@Id", customerId)
            con.Open()
            cmd.ExecuteNonQuery()
            con.Close()
        End Using
    End Using

    BindGridView()
End Sub

Protected Sub Save(ByVal sender As Object, ByVal e As EventArgs)
    Dim constr As String = ConfigurationManager.ConnectionStrings("constr").ConnectionString
    Using con As SqlConnection = New SqlConnection(constr)
        Using cmd As SqlCommand = New SqlCommand("UPDATE Customers SET Name = @Name,Country = @Country WHERE CustomerId = @Id", con)
            cmd.CommandType = CommandType.Text
            cmd.Parameters.AddWithValue("@Id", lblId.Text.Trim())
            cmd.Parameters.AddWithValue("@Name", txtName.Text.Trim())
            cmd.Parameters.AddWithValue("@Country", txtCountry.Text.Trim())
            con.Open()
            cmd.ExecuteNonQuery()
            con.Close()
        End Using
    End Using

    lblId.Text = String.Empty
    txtName.Text = String.Empty
    txtCountry.Text = String.Empty

    BindGridView()
End Sub

Screenshot