Disclaimer: the following features are only available for paid plans. Please upgrade your free plan if you need more security in your account.
Auto Logout
In your account settings under the tab Logged in users you can set a time in minutes when a user will be auto logged out, if he is not active.
Manually logout a user
In your account settings under the tab Logged in users you can also logout current logged in users. In the following screenshot you see currently logged in users. You can press the Logout button to logout an individual user.