Hide checked (selected) GridView row on Button Click using C# in ASP.Net

I have GridView and checkboxes, while select check box and click on button then row should be hide.

namespace Plant_Enrty_system
{
    public partial class cisf_approv : System.Web.UI.Page
    {        
        protected void button_Click(object sender, EventArgs e)
        {
            string pass_id = string.Empty;
            DataTable dt = new DataTable();
            try
            {
                foreach (GridViewRow row in GridView1.Rows)
                {
                    pass_id = Convert.ToString(GridView1.DataKeys[row.RowIndex].Value);
                    CheckBox cb = (CheckBox)row.FindControl("chkSelect");
                    if (cb.Checked)
                    {
                        string cisf_flag = cb.Checked ? "Y" : "N";
                        string constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
                        using (SqlConnection con = new SqlConnection(constr))
                        {
                            SqlCommand cmd = new SqlCommand("UPDATE Customers SET cisf_flag = @cisf_flag where pass_id=@pass_id");
                            cmd.Connection = con;
                            cmd.Parameters.AddWithValue("@cisf_flag", cisf_flag);
                            cmd.Parameters.AddWithValue("@pass_id", pass_id);
                            con.Open();
                            string isUpdated = Convert.ToString(cmd.ExecuteNonQuery());
                            con.Close();
                        }
                    }
                }
            }
            catch (Exception ex)
            {
                Response.Write("Error occured: " + ex.Message.ToString());
            }
            finally
            {
                pass_id = string.Empty;
            }

            System.Threading.Thread.Sleep(8000);
        }
    }
}