User can not logout if login with FB

Question

I make a test with FB and I realized that if the user registers or login with FB, then is impossible to close session, even if the user has logged out from FB.

Reason :

Q2 Logout button disappears.

Any idea how resolve this, on my test i make the test with my own accont, now I can not logged out or enter like admin (lol)

BR

Answer 1

Log out temporarily with chrome:

Ctrl + Shift + I

Application > Storage > Cookies. Click to site, Clean.