Facebook provides two options - deactivate and delete.
Deactivating facebook account
If you deactivate your account, you can, at any time, reactivate your account by simply logging into your facebook account. When you come back, you will be able to see all your timeline data and your friends list will also be restored.
Follow this link to deactivate your account: http://www.facebook.com/help/www/214376678584711
Deleting a facebook account
Facebook also allows, kind of, permanently deleting your account. Choose this option carefully, since, once you delete the account, facebook doesn't allow you to reactivate your account, even though Facebook retains your account details and user data, due to Fedaral laws. ederal rules enforces facebook to retain all the user data, even if the user closes the account.
Link for deleting facebook account: https://www.facebook.com/help/delete_account (it is obvious that you will need to login to delete your account).
In summary, you have two options, deactivating your facebook account and deleting the facebook account. Though your data is retained with facebook, no matter what option you choose, you will never be able to restore a deleted account.
For more information on this kindly go though this facebook help article: http://www.facebook.com/help/224562897555674