Right way to delete the idle threads from a smart thread pool

I have been using the C# smart thread pool to do some work but found the current smart thread pool release DOES NOT anything about the removed "idle threads". This may or may not cause smart thread pool memory leaks.
 
In the smartthreadpool.ProcessQueueItem() method there are several times the method calls InforComleted() method when a idle thread(s) is timed out. But the InformCompleted() just removes the thread from the dictionary and didn't the delete these threads:

private void InformCompleted()
{
   if(_workerThreads.Contains(Thread.CurrentThread))
   {
      _workerThreads.Remove(Thread.CurrentThread);
   }
}

I'm wondering if there is anyone out there already solved this problem and test it out.
 
Thank you very much.
 
Best regards,
CodeBeetle123