Deactivating your account does not fully delete it. When you deactivate your account, Facebook saves all of your settings, photos, and information in case you decide to reactivate your account. ... To delete your Facebook account, follow this link to the Delete My Account page.

How long before a deactivated Facebook account is deleted?

Facebook Waits 14 Days Before Deleting Account

The social network said there is no limit on how long a user can keep her account deactivated. But if a Facebook user really wants to make the separation permanent, she can choose to delete the account altogether.

Will Facebook delete my deactivated account automatically?

Account Deletion

Like deactivation, Facebook will not delete your account for inactivity. It's something you must do from your “Account Settings” page. Once deleted, your account cannot be reinstated. All content, including your Timeline, photos, friend lists and other personal data, are deleted.