thank you for direction to solve my problem.
Here is final code:
procedure TForm1.FormCreate(Sender: TObject);
var aC,aR:integer;
begin
for aC := 0 to 4 do begin
myGrid.AddRow();
aR:=myGrid.LastAddedRow;
myGrid.Cell[colBtn.Index,aC].Empty:=true;
end;
colBtn.HideWhenEmpty:=true;
end;
procedure TForm1.myGridBeforeSelect(Sender: TObject; var ACol, ARow: Integer;
Key: Word; Shift: TShiftState);
begin
if(myGrid.SelectedRow<>-1)then begin
myGrid.Cell[colBtn.Index,myGrid.SelectedRow].Empty:=true;
end;
end;
procedure TForm1.myGridSelect(Sender: TObject; ACol, ARow: Integer);
begin
myGrid.Cell[colBtn.Index,myGrid.SelectedRow].Empty:=false;
myGrid.Repaint();
end;