Logging Out And Disconnecting
From Facebook Developer Wiki
You need to handle users logging out of your site differently from users disconnecting from your site.
For information on how to log users out of your Connect site or application and Facebook, read the appropriate article for:
[edit] Disconnecting Users
Users should have the option to either delete their account on your site or to permanently disassociate their account on your site from their Facebook account.
To sever the connection with Facebook, you should use the auth.revokeAuthorization method in the PHP client library. This method can't be called from the JavaScript client yet (however, this feature is coming soon).
If the user severs their connection with your website via the Facebook Edit Applications page, Facebook pings the Post-Remove URL.
Any Facebook Connect site that stores data about the user must register a Post-Remove URL (specified in your application settings) and must honor removal requests received via this URL. When you are notified that the user has disconnected, you must remove all cached information about that user from your system. Please see the Facebook Platform Terms of Service for more information about caching information.
[edit] Reclaiming Deactivated Users
If a user deactivates his or her Facebook account, you are able to give the user the option to set up an account specific to your site. You need to specify an Account Reclamation URL in your application settings. For more information, see Reclaiming Accounts.
