They changed the UI a bit, even if you're not using the new control panel. Basically it's more tied in with your Google account. If you click on your email address up in the upper right corner, that should get you the sign out.
10:45 pm on Dec 11, 2013 (gmt 0)
The following 8 messages were cut out to new thread by martinibuster. New thread at: google_adsense/4631209.htm [webmasterworld.com] 11:51 am on Dec 16, 2013 (utc -8)