The currently active users are displayed in 'session management'. The system allows admins to terminate a user's session.

The lifespan of a session is governed by the ASP.Net session timeout value. This value is displayed in the installation check page. When a session is idle for longer than the session time out value, it is automatically ended and the corresponding user will need to log in again.

You may delete an active session (e.g. when it's been idle for a long period of time; perhaps the end-user forgot to log out properly), but you cannot delete your own session.