I’ve noticed a disturbing trend among Facebook users: the myth that Facebook does not allow you to delete your account, and only allows you to deactivate it.
Deactivating your Facebook account does little to protect your privacy; while it may keep you from posting those drunken photos from future company Christmas parties, your data remains intact. It’s difficult to tell, and I can’t test it without opening an account, but the unwritten message is that data posted on others’ walls, groups, and fan pages will still be associated with your name unless you permanently delete the account. If you’re quitting Facebook to protect your reputation with future employers, for example, this doesn’t cut it.
Read the relevant sections of the privacy policy for yourself:
Deactivating or deleting your account. If you want to stop using your account you may deactivate it or delete it. When you deactivate an account, no user will be able to see it, but it will not be deleted. We save your profile information (connections, photos, etc.) in case you later decide to reactivate your account. Many users deactivate their accounts for temporary reasons and in doing so are asking us to maintain their information until they return to Facebook. You will still have the ability to reactivate your account and restore your profile in its entirety. When you delete an account, it is permanently deleted from Facebook. You should only delete your account if you are certain you never want to reactivate it. You may deactivate your account on your account settings page or delete your account on this help page.
Limitations on removal. Even 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. However, your name will no longer be associated with that information on Facebook. (For example, if you post something to another user’s profile and then you delete your account, that post may remain, but be attributed to an “Anonymous Facebook User.”)
Deleting your account is fairly straightforward, but it does take 14 days to take effect. During that time, you must not log back in, even by accident, or you’ll have to start over.
It seems one of the ways Facebook continues to secure its user base of over 400 million is simply by making the option to leave so obscure that few know it exists. You may be free to leave at any time, but first you have to find the exit.