josh@g4m30v3r1d3-ThinkPad-T400s:~$ deluser g4m30v3r1d3
/usr/sbin/deluser: Only root may remove a user or group from the system.
josh@g4m30v3r1d3-ThinkPad-T400s:~$ sudo deluser g4m30v3r1d3
[sudo] password for josh: 
Removing user `g4m30v3r1d3' ...
Warning: group `g4m30v3r1d3' has no more members.
userdel: user g4m30v3r1d3 is currently used by process 3513
/usr/sbin/deluser: `/usr/sbin/userdel g4m30v3r1d3' returned error code 8. Exiting.
josh@g4m30v3r1d3-ThinkPad-T400s:~$