How to delete a single cell value when ActivateCurrentCellBehavior is set to none in WinForms GridControl?

this.gridControl1.ActivateCurrentCellBehavior = GridCellActivateAction.None;
this.gridControl1.ListBoxSelectionMode = SelectionMode.One;

this.gridControl1.KeyDown += new KeyEventHandler(gridControl1_KeyDown);

void gridControl1_KeyDown(object sender, KeyEventArgs e)
{
    if (e.KeyCode == Keys.Delete)
    {
        int rowIndex = this.gridControl1.CurrentCell.RowIndex;
        int colIndex = this.gridControl1.CurrentCell.ColIndex;
        this.gridControl1[rowIndex, colIndex].CellValue = null;
        e.Handled = true;
    }
}

Me.gridControl1.ActivateCurrentCellBehavior = GridCellActivateAction.None
Me.gridControl1.ListBoxSelectionMode = SelectionMode.One

AddHandler Me.gridControl1.KeyDown, AddressOf gridControl1_KeyDown

void gridControl1_KeyDown(Object sender, KeyEventArgs e)
 If e.KeyCode = Keys.Delete Then
  Dim rowIndex As Integer = Me.gridControl1.CurrentCell.RowIndex
  Dim colIndex As Integer = Me.gridControl1.CurrentCell.ColIndex
  Me.gridControl1(rowIndex, colIndex).CellValue = Nothing
  e.Handled = True
 End If