# ps aux | grep ssh
Will print something like:
root 1450 0.0 0.0 5432 620 pts/0 S+ 02:46 0:00 grep ssh
root 26528 0.0 0.0 5068 1016 Ss Jul28 0:00 /usr/sbin/sshd
With this you can execute the command
# kill -15 26528
This was the user session for root that I never closed because it timed out.. So this is what I did.