Linux add/remove an existing user to a gorup edit

Add an existing user to a group

# usermod -a -G GROUP USER

Remove an existing user form a group

# gpasswd -d USER GROUP

http://www.howtogeek.com/50787/add-a-user-to-a-group-or-second-group-on-linux/ http://unix.stackexchange.com/questions/29570/how-do-i-remove-a-user-from-a-group