static void Main(string[] args)
{
RegisteredWaitHandle handle1 = TaskScheduler.ScheduleDelayedJob(new PrintJob(), "hello", new TimeSpan(0, 0, 2));
RegisteredWaitHandle handle2 = TaskScheduler.SchedulePeriodicJob(new PrintJob(), "hi", new TimeSpan(0, 0, 1));
Thread.Sleep(5000);
handle2.Unregister(null);
Thread.Sleep(3000);
}