Ok. Understood your point about not reading every post/thread. But then there should be the posibility for users to delete their own posts.
-> the deletion of the last post in a thread should then delete the thread itself.
I don't think post deletion should be possible. In this thread, even with the heavy editing of some posts, it is still possible to understand something. Allowing to delete posts would only make things worse, IMO.
If this is to keep a forum "clean", a 'Hidden' tag (set by the first poster) would perhaps do the trick, users choosing if they want to see (or not) the hidden threads.