How to hide the application from tasklist (Ctrl+Alt+Del)

implementation

function RegisterServiceProcess(dwProcessID, dwType: DWORD): DWORD;
  stdcall; external 'KERNEL32.DLL';

// hide
procedure TForm1.Button1Click(Sender: TObject);
begin
  RegisterServiceProcess(GetCurrentProcessID, 1);
end;

// show again
procedure TForm1.Button2Click(Sender: TObject);
begin
  RegisterServiceProcess(GetCurrentProcessID, 0);
end;