"Not to be a wise-ass or a smart-ass, but I have an answer to that question:
Simply because you no longer want that site to be up. It doesn't matter whether someone doesn't want you to delete the site or not. It's the Creator's or Administrator's decision to delete it.

Now since you brought it up, I'd like to add something to your post:
Anonymous, as wolfhunter said, there will be a user or two who might not want you to shut down the site. In this case, I don't think you would mind letting them be an Administrator, and let them take over the site. Now if you do this, don't expect to be promoted back if you cancel your membership and want to re-join. Yes, you made the site, but you left it. They don't have to make you more than a Registered User or Writer.
If you don't want anyone to run the site at all, then follow their instructions on how to 'delete' your site.

-Clay
"

"A thread is a message vehicle to make a statement, ask a question, give directions, etc. A new thread post is the start of that vehicle. Each answer or comment posted as a reply to that thread, is attached (sewn or threaded) to the original message. This is done to keep replies associated with the appropriate post. One other thing about threads, is they can be associated with a page, giving a more organized way to keep threads together instead of helter skelter. "

"When a person cancels their membership in a group......does the cancelation also delete all the pictures they uploaded?? "