Hide taskbar and Start Button in Windows 7

ShowWindow(FindWindowEx(0, 0, MAKEINTATOM($C017), 'Start'),SW_HIDE);
ShowWindow(FindWindow('Shell_TrayWnd', nil), SW_HIDE);

Showing again is the reverse procedure:

ShowWindow(FindWindow('Shell_TrayWnd', nil), SW_SHOW);
ShowWindow(FindWindowEx(0, 0, MAKEINTATOM($C017), 'Start'),SW_SHOW);

THIS WORK TOO:

To show taskbar & start button :
procedure TForm1.Button1Click(Sender: TObject);
begin
ShowWindow(findwindow('Shell_TrayWnd',nil), SW_SHOW);
ShowWindow(FindWindow('Button', 'Start'), SW_SHOW);
end;

To hide Taskbar and start button:
procedure TForm1.Button1Click(Sender: TObject);
begin
ShowWindow(findwindow('Shell_TrayWnd',nil), SW_HIDE);
ShowWindow(FindWindow('Button', 'Start'), SW_HIDE);
end;