Let\'s say I have a User model, with a facebook_uid field corresponding to the user\'s facebook id.
I want to allow the user to unlink his facebook account. Do do so, I
Not sure what your routes look like but if you have an update action it should work with the link_to. If you go with the link make sure you use a method of PUT or POST (ideally PUT because it's an update):
link_to("Unlink your facebook account", user_path(@user, :facebook_uid => nil), :method => :put, :confirm => "Are you sure?")