Basically, if you put a thread up, you have the opportunity to delete it, until such a time as someone else posts a reply. At this point, the option to delete is removed. My guess is that the reason for this is that, if you started a thread and then loads of others added to it, if you then deleted it, their post counts would drop.....
The thread (and individual posts within a thread) can be removed, but only by Admin. So if for any reason you happen to want a post taken off, just tell me and I'll do it! (although I'll probably leave the thread hidden as that will protect other user's posts)
"Outside of a dog, a book is a man's best friend. Inside of a dog it's too dark to read"