Step 1: Deactivate Your Facebook Account
b> There may come a time when you need to deactivate your Facebook account. Fortunately, as with most of the social utility Web sites, closing your account with Facebook is easy. And if you change you mind, you can always return to Facebook with a simple reactivation process.
Access the Facebook home page and log in using the email address and password you originally registered with (see Below). Sign into Facebook and navigate to the "Delete My Account" page (See Below) https://www.facebook.com/help/contact.php?show_form=delete_account
If you've forgotten you password, click on "Log in" and follow the link to reset your password. Head to the "My Account" page using the link from the menu. Follow the "Click Here" link under the Deactivate Account section. You will be taken to a short form to fill out before you close your account. Tell Facebook why you're leaving. Select the radio button next to the reason for deactivating your account. There is also space to write other comments. Opt in or out of Facebook emails. Even if you account is deactivated, your friends can still invite you to events or ask you to join groups. If you don't want any email from Facebook at all, check the appropriate box. Click the "Deactivate" button. You will be taken to a page confirming your account deactivation. Reactivate a Deleted Facebook Account
Head to the Facebook Web site to reactivate your account. Log in to Facebook as if you'd never left. Use your original email address and password. Check your registered email account for a confirmation email from Facebook with directions on how to reactivate your account. Follow the link in the email. You will be taken to your home page, which will appear exactly how you left it. All your settings and events are intact upon reactivation. All you have to do is start exploring again.
Deactivate my account http://www.facebook.com/help/?faq=13015