I recently ran into “The maximum number of user sessions has been reached” error when working on a new Cisco UCS-E160D.

To fix things you can SSH to the CIMC address and run:

show user-session

To change to a particular session from the resulting list, note the session index numbers from the user-session list and run:

scope user-session sessionindex

To end the session you just switched to, run:

terminate

To exit the scope of that session, run:

exit