How to delete a Facebook & Yahoo account for good?

[RyanH]

They're stored in a database that you don't have access to. You can't ensure that it's ever actualy deleted.

What you can do is delete the content from your facebook page and change your e-mail address that's tied to the account to an e-mail address that doesn't exist, and then change the account passwords (for both facebook and yahoo) to a random password (try rolling your fist on the keyboard).

Now you will never be able to guess the passwords and you wont be able to retrieve them

hope this helps,
Ryan