Очистить ячейки в TStringGrid

Вариант 1:

Source: https://www.swissdelphicenter.ch

procedure TForm1.Button1Click(Sender: TObject);
 var
   i, k: Integer;
 begin
   with StringGrid1 do
     for i := 0 to ColCount - 1 do
       for k := 0 to RowCount - 1 do
         Cells[i, k] := '';
 end;

Вариант 2:

Source: https://www.swissdelphicenter.ch

// Many times faster! 
procedure TForm1.Button2Click(Sender: TObject);
var
  I: Integer;
begin
  for I := 0 to StringGrid1.RowCount - 1 do
    StringGrid1.Rows[I].Clear();
end;