I believe the "delete" button is only active for a short time in the "edit" area . . . to allow one to remove a boo-boo. It may last only minutes or an hour or so . . . however it has been set up for this site.
If all else fails you could send a PM to the moderators and ask them to delete your post. They are busy people but they could probably delete it for you, if they desired.
T.