To reproduce:
  radGridView1 = new RadGridView();
            radGridView1.Dock = DockStyle.Fill;
            
            Controls.Add(radGridView1);

            t.Columns.Add("ID");
            t.Rows.Add(7);
            t.Rows.Add(5);
            t.Rows.Add(8);
            t.Rows.Add(4);
            t.Rows.Add(9);
            radGridView1.DataSource = t;
            radGridView1.Columns[0].Width = 100;

With the code above, start the app, sort the grid ascending and select the row with value 8. Use the following code on a button to delete the row with value 5:
  private void radButton1_Click(object sender, EventArgs e)
        {
            t.Rows[1].Delete();
        }

In this case, the current should be the row with value 8, not the one with value 7 as is.