Disable Guest Account on Ubuntu 12.10

I wanted to disable the "Guest" account on Ubuntu 12.10. A guest account allows anyone to use the computer without login credentials. No username or password is required.  Ubuntu has a guest account enabled by default right through to the current release, Ubuntu 12.10.

To disable the guest account from their Ubuntu 12.04 (Precise Pangolin) or later, we need to remove it from the account list in LightDM - this is the greeter screen you see on start-up. LightDM is an X display manager for login interfaces., which replaced the old GDM (Gnome Display Manager).

I ran the following command in the terminal to open /etc/lightdm/lightdm.conf file in the gedit text editor.

$ sudo gedit /etc/lightdm/lightdm.conf

Mine contains only:
[SeatDefaults]
user-session=ubuntu
greeter-session=unity-greeter

I added the following line to the end of the lightdm.conf file. Then I saved the file and closed the editor.

allow-guest=false

Finaly I restarted the LightDM using following command. Not that If you don't like to restart LightDM, you may wait untill the next re-boot of your system to take effect of the above modification.

Please note that, If you are going to restart lightdm using the following command, first save all unsaved documents. The command might close all the running applications.

$ sudo restart lightdm

You may use the above steps with your own risk. It worked fine with me... :)