We do not currently allow players to delete their own posts, to prevent abuse. However, you can report your topic and request a deletion or a lock to flag it up to a moderator if you want to
Be aware that if you want a topic deleted rather than locked or moved, it is better to request this early on. We will not usually delete topics that have already gained traction (such as a good number of useful replies) unless there is a very good reason to do so, as the deletion will negatively impact those user's post counts and search histories as well as your own.