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
excellent