Your account can be deleted on request, and some have. It's not a particularly difficult task.

Your posts, however, will not. There is a combination of reasons for this: one; the older that posts are, the harder it is to find them for the moderators for deletion. Two; the more posts you need deleted, also makes it harder. Three and the most key factor is what The Gimwinkle already said; once it's out, it's out. Even if you delete a post, you can never guarantee that it hasn't been downloaded, archived, or even hard printed, elsewhere. So the usefulness of deleting is extremely low for protection. And it drops exponentially from the moment of posting onwards. Anything older than a day has already been watched and saved by our enemies, barring the occasional downtimes preventing any access to GC.