I know that there’s a way to suspend the Facebook account and it should be removed after 2 weeks.
However I would like to immediately and definitively remove my account, so that in their servers would no longer be any reference to me. In many countries that have privacy laws, companies are forced by law to provide a full opt-out option.
Short answer : you can’t.
Long answer : just remove all the information you have on your account, change privacy settings to the lowest possible.
This article explains how to remove your account : http://www.smashingmagazine.com/2010/06/11/how-to-permanently-delete-your-account-on-popular-websites/
But be warned that it is not immediately removed (they say at least 14 days).