Ubuntu 13.04 Raring Ringtail enables guest login by default, it means that anyone can use your computer (with limited access) without any login credential. In some cases, this is very useful because it allows our friend or family "borrow" the computer for a certain period. The guest session might put your computer at risk by allowing unwanted users access the computer. Fortunately, Ubuntu 13.04 Raring Ringtail allows us to disable guest session, here's the tutorial.

Disable Guest Login
To disable Guest Login or guest session, simply open Terminal and execute the following command:
  • sudo /usr/lib/lightdm/lightdm-set-defaults -l false
You will be asked for root password, type it and hit Enter. Once done, you have to restart the computer in order to see the changes. Alternatively, you can run the following command instead of restarting:
  • sudo restart lightdm

As shown in the picture above, there is no guest login option available.

Enable Guest Login
In case, you change your mind and want to enable the guest login again, simply execute the following command:
  • sudo /usr/lib/lightdm/lightdm-set-defaults -l true
Once enabled, restart the computer or execute the following command:
  • sudo restart lightdm
Regards :)