Disable Guest Session on Ubuntu 12.04

Disable Guest Session on Ubuntu 12.04

gksu gedit /etc/lightdm/lightdm.conf

Add allow-guest=false to the end so your final result should look like:

/etc/lightdm/lightdm.conf

[SeatDefaults]
greeter-session=unity-greeter
user-session=ubuntu
allow-guest=false

Restart the display manager:

sudo restart lightdm

Reference:
http://askubuntu.com/questions/62564/how-do-i-disable-the-guest-session