How do you logout of a multisite privacy password-protected page

I have installed the Multisite Privacy Plugin. On individual blogs, I've gone into Settings>Reading and set up "Anyone that visits must first provide this password" and put in password. This works great BUT how do they "LOGOUT" of the site? I want them to have to log back in after a timeout because if they use a public computer this would be open to anyone to see and use.
The settings in Network Admin are as follows:
Available Options (all are checked)
Default Setting -Allow all visitors to all sites.
Thank you for your help.