The rule used by many forums is that when you sign up, you agree to certain things - and many forum users get really cross when they spent time answering questions only to have their effort binned. As a result many forums will allow you to request a closure - so new posts can't be added, but it's rare to delete them - they're there for ever. On the forum I moderate we delete topics that break rules, contain legal time bombs or perhaps dangerous incorrect info. We never delete a topic that has lots of views or responses unless the rules get broken. Sometimes, we might be willing to perhaps edit or tweak something that is embarrassing or 'difficult' - but I looked at your posts and there's nothing controversial is there? If you don't respond to a topic, it soon drops off the leader board as most readers simply click on the 'new posts' button.