You may ask for a site review. The guidelines are in the FAQs.
As @John_Betong says, there is an edit window (5 hours, I believe), after which only moderators can edit a post.
You can delete your own posts within the edit window, unless it is the opening post of a topic. We do not generally delete topics where there have been responses made, but may do so in exceptional circumstances. However, it is safer not to post anything you don't want to become public, as these forums are crawled and indexed by search engines.
I suggest you read the FAQs for more information about the forums.