== ISSUE THIS COMMAND
[xxx@devxxx ~]$ screen -ls
== SCREEN RESPONDS
There are screens on:
        23487.pts-0.devxxx      (Detached)
        26727.pts-0.devxxx      (Attached)
2 Sockets in /tmp/uscreens/S-xxx.
== NOW KILL THE ONE YOU DONT WANT
[xxx@devxxx ~]$ screen -X -S 23487.pts-0.devxxx kill
or
[xxx@devxxx ~]$screen -S 23487 -X quit
== WANT PROOF?
[xxx@devxxx ~]$ screen -ls
There is a screen on:
        26727.pts-0.devxxx      (Attached)
1 Socket in /tmp/uscreens/S-xxx.
REFERENCES
http://stackoverflow.com/questions/1509677/kill-detached-screen-session