deleting rows in gridview..

after selecting the rows through checkbox in first gridview and transfering them to second gridview i want the selected rows to get deleted from the first gridview..i want to delete the rows only in the front end and not from database since i have used sql data source to fill the first gridview..is this possible..below is the code which i have used..

 foreach (GridViewRow row in GridView1.Rows)
            {
                string upstr = "UPDATE emp SET flag = '1' WHERE empId = ";
                CheckBox ch = (CheckBox)(row.FindControl("chkbx1"));

                if (ch.Checked == true)
                {
                    int Id = Convert.ToInt32(GridView1.DataKeys[row.RowIndex].Value);
                    idArr.Add(Id);

                    upstr += "'" + Id + "'";
                    conn = new SqlConnection(constr);
                    conn.Open();
                    SqlCommand comm = new SqlCommand(upstr, conn);
                    comm.ExecuteNonQuery();
                    conn.Close();

                    GridView1.DeleteRow(Id);

                    //row.Visible = false;
                    ch.Checked = false;
                }
            }

when i am compiling this am getting ""Deleting is not supported by data source 'empReq' unless DeleteCommand is specified."