This tutorial shows how to terminate a Unix screen session. This can be accomplished most of the time by calling the exist command; however, the command shared here is mostly useful for unresponsive sessions.
In case you are interested in learning more about the Unix command screen, the video below is great
Terminate A Screen Session
Terminating a screen session is simple; you can simply use the command below:
$ screen -X -S [session # you want to kill] kill