When You Cancel Your Facebook Account Do All Your Comments to Your Friends Go Away Too?by Aaron Parson
Facebook has two ways you can remove the content you've posted to the site in bulk: account deletion and deactivation. Deleting your account permanently erases everything you've ever posted to the site. Deactivation hides your profile and posts from view, but the content remains stored in the site's database. With a deactivated account, some of your activity still appears to your friends.
Effects of Deleting Your Facebook
If you never want to return to Facebook, you can request permanent account deletion. Deleting your account erases everything you've posted to Facebook, including comments on your friends' pages, private messages to friends, and your friends list. If you decide to use Facebook again after deleting your account, you need to create a new account and start from scratch.
Deactivating your account hides your profile from view, so other users can't search for you. Your posts and publicly visible comments also vanish, but messages you sent your friends privately do not go away. Friends can still open and read those messages, even though they cannot write back until you reactivate your account. Reactive your account by going to the Facebook site and logging in as usual.