If you're all set to delete your Facebook account, here's how to do that. Facebook offers you two alternatives: two alternatives: deactivate or delete.
Deactivating Facebook account
Deactivating Facebook account couldn't be simpler. Open Facebook, click the drop-down menu at the top-right of your screen and choose Settings. Click General on the top left, Edit next to "Manage Account." Scroll down and you'll see a "Deactivate My Account" link at the bottom. (Here's the direct link).
If you're on your mobile phone, such as using Facebook for iOS, similarly go to Settings > Account Settings > General > Manage Account > Deactivate.
"Deactivation" is not the same as leaving Facebook. Yes, your timeline will vanish, you won't have access to the website or your account through mobile apps, friends can't post or contact you, and you'll lose access to all those third-party services that use (or need) Facebook for login. However Facebook does not delete the account. Why? So you can reactivate it later on.
Simply in case that expected re-activation isn't in your future, you should download a copy of all your data on Facebook-- posts, pictures, videos, talks, and so on-- from the settings menu (under "General").
Facebook Account Deletion.
To completely delete your Facebook account permanently, go to the Delete My Account page at facebook.com/help/delete_account. Simply be aware that, per the Facebook data use policy, "after you remove information from your profile or delete your account, copies of that information may remain viewable elsewhere to the extent it has been shared with others, it was otherwise distributed pursuant to your privacy settings, or it was copied or stored by other users.".
Translation: if you wrote a comment on a friend's status update or image, it will remain even after you delete your own profile. Some of your posts and images may hang around for as long as 90 days after deletion, also, though simply on Facebook servers, not live on the website.