Disabling guest feature on ubuntu 12

I just started using Ubuntu 12 and I have been worried about the guest(for security reasons) so I did a bit on research(can't remember the website I pulled this from exactly)

navigate to the TERMINAL and type:

gksudo gedit /etc/lightdm/lightdm.conf

(password might be required.)

add the following line

allow-guest=false

save and exit file

after adding the above line you should see something similar to the following:

[SeatDefaults]

user-session=ubuntu

greeter-session=unity-greeter

allow-guest=false

finally restart lightdm by typing the following into the terminal

sudo restart lightdm