A long-standing policy on MartialTalk is that we rarely delete content, unless it violates a rule, like unauthorized advertising. You have a brief window after posting to edit the post. If you really feel you must have a post deleted, you can report it, and explain why you want it deleted. It needs a much better justification than "I put my foot in my mouth" or "I wish I'd never said that..."
There may be differences under Xenforo that allow or allowed you to delete a post, and of course you could have edited it to a point that it was gone for all intents and purposes during the window... But the policy has been only to delete content in rare and special circumstances.
There's a 60 minute window in which you can edit and possibly delete a post. After that, policy has always been no deletions without a reason better than "I changed my mind". The idea is on other sites long standing discussions have been gutted when someone got butt hurt and went on a deletion spree, and we wanted to make sure that didn't happen here.