Replace Excel Null Row with value using c#

private void pbDelete_Click(object sender, EventArgs e)
        {
            if (MobileNumber == "")
            {
                MessageBox.Show("Please select a Name !..");
            }
            else
            {
                if (MessageBox.Show("Do you realy want to delete this data?", "", MessageBoxButtons.YesNo, MessageBoxIcon.Question) == DialogResult.Yes)
                {
                    if (index != -1)
                    {
                        string conn = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + Path.GetDirectoryName(Application.ExecutablePath) + "\\Taas SMS.xls;Extended Properties=Excel 8.0;";
                        //oledbConn.Open();
                        //cmd1 = new OleDbCommand();
                        //cmd.Connection = oledbConn;
                        //cmd.CommandText = "INSERT INTO ExecutiveMember (Name,Designation,TravelAgent, MobileNumber) values ('" + dt.Rows[i][0] + "', '" + dt.Rows[i][1] + "','" + dt.Rows[i][2] + "', '" + dt.Rows[i][3] + "')";
                        //cmd.ExecuteNonQuery();
                        //oledbConn.Close();
                        OleDbConnection oledbConn1 = new OleDbConnection(conn);
                        oledbConn1.Open();
                        OleDbCommand cmd1 = new OleDbCommand();
                        cmd1.Connection = oledbConn1;
                        cmd1.CommandText = "select * from ExecutiveMember";
                        OleDbDataAdapter da = new OleDbDataAdapter(cmd1);
                        DataTable dt1 = new DataTable();
                        //dt1.Clear();
                        da.Fill(dt1);

                        OleDbConnection oledbConn = new OleDbConnection(conn);
                        oledbConn.Open();
                        OleDbCommand cmd2 = new OleDbCommand();
                        cmd2.Connection = oledbConn;
                        cmd2.CommandText = "update ExecutiveMember set Name='',Designation='',TravelAgent='',MobileNumber='' where MobileNumber='" + dt1.Rows[index][3] + "'";
                        cmd2.ExecuteNonQuery();
                        oledbConn.Close();

                        //DataRow dtRowDelete = dt1.Rows[index];
                        //dtRowDelete.Delete();
                       
                        //dt1.AcceptChanges();
                        da.Update(dt1);

                        dgvExecutiveMember.DataSource = dt1;
                        
                        //conn = new OleDbConnection();
                        //conn.ConnectionString = gm.ConnectionString;
                        //conn.Open();
                        ////cmd = new OleDbCommand("select * from ExecutiveMember where MobileNumber='" + MobileNumber + "'", conn);
                        //cmd = new OleDbCommand("select * from ExecutiveMember", conn);
                        //da = new OleDbDataAdapter(cmd);
                        //dt.Clear();
                        //da.Fill(dt);
                        //DataRow dtRowDelete = dt.Rows[index];
                        //dtRowDelete.Delete();
                        //dt.AcceptChanges();
                        //da.Update(dt);

                        
                        OleDbConnection oledbConn2 = new OleDbConnection(conn);
                        oledbConn.Open();

                        //conn = new OleDbConnection();
                        OleDbCommand cmd = new OleDbCommand("SELECT * FROM [ExecutiveMember]", oledbConn2);
                        OleDbDataAdapter oleda = new OleDbDataAdapter();
                        oleda.SelectCommand = cmd;
                        DataSet ds = new DataSet();
                        oleda.Fill(ds, "ExecutiveMember");

                        int rowcount = ds.Tables[0].Rows.Count;
                        oledbConn.Close();

                        
                        

                        for (int i = 0; i < rowcount-2; i++)
                        {
                            
                            oledbConn.Open();
                            cmd = new OleDbCommand();
                            cmd.Connection = oledbConn;
                            cmd.CommandText = "update ExecutiveMember set Name='" + dt1.Rows[i][0] + "',Designation='" + dt1.Rows[i][1] + "',TravelAgent='" + dt1.Rows[i][2] + "',MobileNumber='" + dt1.Rows[i][3] + "' where MobileNumber='" + dt1.Rows[i][3] + "'";
                            //cmd.CommandText = "INSERT INTO ExecutiveMember (Name,Designation,TravelAgent, MobileNumber) values ('" + dt1.Rows[i][0] + "', '" + dt1.Rows[i][1] + "','" + dt1.Rows[i][2] + "', '" + dt1.Rows[i][3] + "')";
                            cmd.ExecuteNonQuery();
                            oledbConn.Close();
                            Clear();

                            
                        }

                        //    conn = new OleDbConnection();
                        //    conn.ConnectionString = gm.ConnectionString;
                        //    conn.Open();
                        //    cmd = new OleDbCommand();
                        //    cmd.Connection = conn;

                        //    cmd.CommandText = "INSERT INTO ExecutiveMember (Name,Designation,TravelAgent, MobileNumber) values ('" + dt.Rows[i][0] + "', '" + dt.Rows[i][1] + "','" + dt.Rows[i][2] + "', '" + dt.Rows[i][3] + "')";
                        //    cmd.ExecuteNonQuery();
                        //    conn.Close();
                        //    Clear();
                        //    FillGrid();
                        //}
                         //conn.Close();

                        
                        Clear();
                        MobileNumber = "";
                        //FillGrid();
                                                                       
                        index = -1;
                        MessageBox.Show("Data Deleted!...");
                                                
                    }
                }
                else
                {

                }
            }
            
        }