Only the original author can edit their own posts. That is how it should be.
As an owner, I believe only way I can get rid of a post is to contact WGT and ask them to do it for me.
If it's an offensive enough post, kick the person from the club, but only the owner can do that. Eventually, the post will fall far enough down pages on the board and be irrelevant, or contact WGT and ask them to do it sooner.