It's all about permissions. When you get to a certain amount of posts you become what's called a "reservist". They can delete posts, (as in watford1990's case). You're not there yet but when you are then your new usergroup will have that permission. The 10 minute thing was about editing posts after a certain time without "edited by" showing on the post.
You can yes. Go to edit post and you should see a delete post option. Try it on the one you just posted, I can always undelete it later.