We occasionally see reports that users are not able to log out (or stay logged out) of their accounts. This prevents other users from logging in via the same device, and could be a security issue for the user who is currently logged in.
We've almost always found this issue to be related to the specific browser being used. As a workaround, try to use a different browser. Another possible workaround is to close all KA windows/tabs, clear the browser history and then try again.
If your preferred browser is Safari, please go to https://www.khanacademy.org/logout_workaround. You should then be able to log out.
Finally, we recommend clearing your browser cache and cookies if you're still having trouble. Here's an article with screenshots on how to do so: http://www.wikihow.com/Clear-Your-Browser's-Cookies
If, after all that, you still are having trouble with logging out of your Khan Academy account, please submit a support ticket describing all of the steps you took to troubleshoot it, and what browsers you tried.
Original Nov. 05th 2015
Last changed June 16 2016
Ref. logout_to_login, (or logout_nogo_Safari if the workaround helps)