Urg...I haven't been on menewsha for a few months or something...But I realized I couldn't find the button that lets you delete your posts. How do you delete posts? Or is it impossible now?

Alas, users can't delete their own posts at all anymore.

In the instance of accidental or lag-induced double posts, all you need to do is simply report it and a mod will take care of it for you. :)