LPT, If you want to edit what you wrote in the body of the text, click the Edit button on the right with the little pencil symbol. Delete, add, or change and then post it again as you would a reply. Bear in mind that it will be the large square reply space that you normally get when you click the ADD REPLY button, not the Quick Reply space at the bottom of the page. (I habitually use that one first.)
If you need the whole post deleted, you have to email a forum leader (just click the Alert button to the right of the Edit buttom) and ask a FL to delete it and we will.