It is possible to delete a Facebook account permanently. This is what "Computeractive" magazine printed in the issue of 19/3-01/04 2009.
Go to the main Facebook page, then click the 'Help' link.
When the page opens, type 'delete' into the search box at the top, then press Return.
After a moment, Facebook will display a set of instructions that explain what to do and what happens to the account.
After reading the instructions, click the 'here' link at the end of the paragraph.
At the next screen, click the Submit button to continue and then at the next screen, type in the password for the account that has to be deleted, and then type in the required capture words. This is your last chance to change your mind.
Click the Okay button and after a moment the Permanently Delete Account dialogue box appears.
Click Okay to finish.
Note that Facebook still retains the data for a further 14 days. Don't log on during that period and on day 15 the data gets zapped - forever.