How to programmatically detach SQL Server Database using C# .Net

1. Add a connection string with Database name as blank

 <connectionStrings>
    <add name="constr" connectionString="Data Source=.\SQL2008R2;Initial Catalog=;User Id=sa;Password=pass@123"/>
  </connectionStrings>

2. Add the namespaces

using System.Data;
using System.Configuration;

3. Add the code

protected void Page_Load(object sender, EventArgs e)
{
    string databaseName = "TestDB";
    string constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
    using (SqlConnection con = new SqlConnection(constr))
    {
        using (SqlCommand cmd = new SqlCommand())
        {
            cmd.Connection = con;
            cmd.CommandText = "sp_detach_db";
            cmd.CommandType = CommandType.StoredProcedure;
            cmd.Parameters.AddWithValue("@dbName", databaseName);
            cmd.Parameters.AddWithValue("@skipchecks", "true");
            con.Open();
            cmd.ExecuteNonQuery();
            con.Close();
        }
    }
}