How to log off or terminate concurrent root sessions on Linux

What:

Linux server

Problem:

You need to terminate disconnected root sessions.

Solution:

Log on via ssh to the machine.
Run the following command to list all sessions:

# w

Now you cat terminate a session by killing it's parent process, called the session leader.
Find process id with:

# ps -dN | grep pts/<number>

Kill session using process id returned by ps command

# kill -9 <pid>

To terminate a session using username run the following command:

# pkill -KILL -u <username>

To terminate graphical sessions use

# pkill x