Si tienes muchos botones:
Código:
procedure TForm1.Button1Click(Sender: TObject);
var
nCont:Integer;
MiRadio:TRadioButton;
begin
for nCont:=0 to Componentcount -1 do
begin
If Components[nCont] is TradioButton then
begin
MiRadio:=Components[nCont] as TradioButton;
MiRadio.Checked:=False;
end;
end;
end;
Un Saludo.