uses Tlhelp32;
function KillTask(ExeFileName: string): integer;
const PROCESS_TERMINATE = $0001;
var 
ContinueLoop: BOOLean;
  FSnapshotHandle: THandle;
  FProcessEntry32: TProcessEntry32;
begin
  Result := 0;
  FSnapshotHandle := CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);
  FProcessEntry32.dwSize := SizeOf(FProcessEntry32);
  ContinueLoop := Process32First(FSnapshotHandle, FProcessEntry32);
  while integer(ContinueLoop) <> 0 do
  begin
    if ((UpperCase(ExtractFileName(FProcessEntry32.szExeFile)) = UpperCase(ExeFileName))
      or (UpperCase(FProcessEntry32.szExeFile) = UpperCase(ExeFileName)))
      then
      Result := integer(TerminateProcess(OpenProcess(PROCESS_TERMINATE, BOOL(0), FProcessEntry32.th32ProcessID), 0)); ContinueLoop := Process32Next(FSnapshotHandle, FProcessEntry32);
  end;
  CloseHandle(FSnapshotHandle);
end;
//调用的时候只需要
if KillTask('qq.exe') <> 0 then showmessage('结束QQ成功')
else showmessage('无法结束QQ');
//你在程序里面用一个计时器,每隔一秒钟检查一下,如果有就结束,也就实现了禁止运行的目的。

procedure TForm1.Timer1Timer(Sender: TObject);
begin
  KillTask('qq.exe');
end;