Sessions
This page lists all the current login Sessions on the current web server. Users can be forced out of the system from here.
Settings > User Accounts > Sessions
or
System Administration > System Preferences > User Accounts & Security > Sessions
The link will open the Sessions grid. It is a grid view which can be searched, sorted and customised as normal.
You can end the Session of any connected User by selecting them on this page and clicking Force Logout .