Please note this code only runs under Windows 95/98

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

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

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