This site uses facebook to log in/connect. So use the generic method to disconnect from any site, as stated below. This can be found on Gamers Unite too, of course: http://gamersunite.coolchaser.com/message/help#quit_member
URLS:
http://gamersunite.coolchaser.com/
Please note that AccountKiller.com is not associated with the business listed on this page. AccountKiller provides easy-to-understand instructions and guides on how to cancel charges and relationships from the list of businesses on our site, we have no affiliation with these businesses.