on 01-27-2013 10:04 AM
Look in upper left corner of your screen, for something like this:
If that does not appear ... if you see another "sign in" link ... click "sign in" and you will be signed out. Somehow, that made sense to the programmers.
on 01-17-2014 01:40 AM
On the top left corner click 'sign in' (which exists against your user id).
Now sign into eBay.
After this you will see "Hi <your name>" in the top-left corner. Click on the arrow besides it.
Now click 'Sign Out'.
PS: This is indeed a convoluted way to perform a simple task. I do not know with what wisdom eBay programmers have done this.