Mass deletion/edit of posts?

Hey, I've been trying to erase certain parts of my internet history, and it's taking me forever to do it.
If there's a way to delete/edit all the posts I've made on here, I'd really appreciate it if you did this for me.
Oh, and could you please delete this account, if you don't mind?

Edit: I'm sorry about the poor English, I'm a little bit mental.

Didn't your name change everywhere when you changed it?

Google caches my old profile/posts with my original username.

Wait, if they're cashed on google won't deleting them make no difference?

Well, you wouldn't be able to see the whole thing, since they'd open the link and the post wouldn't be there.
I suppose my choice of wording was pretty poor, though. By cached, I mean the names/headers of the links, not the page itself.