My whole delete method() is executing successfully and there is no error,but the records are not being deleted

When debugger is applied the query-line shows no data in textBox1.Text.my code is following:

namespace SeparateConnection
 {
 
 
  class clsGridView
 {
 
     Connection co2 = new Connection();
     //display our global varaible for connection
     SqlConnection myconn3 = new SqlConnection("data source=M-SULEMAN-PC;initial catalog=dbmsLogin;integrated security=sspi");
     public void Delete()
     {
         co2.setconn();
         try
         {
             DialogResult result = MessageBox.Show("Are you sure you want to delete ?", "Message",
                 MessageBoxButtons.YesNo, MessageBoxIcon.Question);
             if (result == DialogResult.Yes)
             {
                 //myconn3.Open();
                 DataTable table2 = new DataTable();
                 frmGridView gd = new frmGridView();
                 SqlDataAdapter myadd2 = new SqlDataAdapter("Delete from tblLogin where UserName ='" + gd.textBox1.Text + "'", myconn3);
                 myadd2.Fill(table2);
 
                 //Sqlcommandbulider to allow changes to database
                 SqlCommandBuilder mybuild = new SqlCommandBuilder(myadd2);
 
                 //Update the database
                 myadd2.Update(table2);
 
                 //Close the connection
                 myconn3.Close();
 
             }
             else
                 return;
 
         }
         catch (Exception error)
         {
             MessageBox.Show(error.ToString());
         }
     }
 

----------when I use the same class for calling and defining the method..there is no problem

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