If your posts are still recent, you can edit them. When you click the edit button, there's actually an option to just delete the post. You have to select Delete the Post and then click it, I'm pretty sure...

Mods can still see deleted posts, but no one else can

EDIT:

Ok, so when you click the edit button, new buttons appear in the bottom right. Save, Go Advanced, Delete, and Cancel. Click Delete and it will expand the box a little more. THEN you'll have to select Delete Message from the Deletion Options, you can enter a reason for the deletion, and then just click Delete this Message