I'd say there's 2 ways to go about this.
One is to disable those tabs at the Drupal level. This can be done via
hook_menu_alter() or for a solution that doesn't need custom code, use the Tab Tamer module.
Tab Tamer is an administration utility that provides easy re-ordering,
hiding, and deactivation of tabs and subtabs. You can also rename tab
The other way, is change your theme to hide those tabs via CSS (e.g. using a
display: none; property). This way the URLs are still accessible to users that don't want to be forced to login via FB (e.g. admins).