If your browser have disabled javascrip, it is impossible to logout from Xwiki.

Well for me the ticket description is misleading: you can always logout without javascript by accessing the /logout/ action URL. Now the problem is that the link to logout is located in the drawer menu that can only be opened with Javascript. Renaming the issue in that way. Note that it's still the case in 15.10 even with the changes made recently on the drawer menu.