There is a Guest Session option in Ubuntu login screen. This user has limited access to the system. But I don’t prefer to have this login. Here is how this login can be disabled.
The display manager in Ubuntu is LightDM. We need to edit the configuration file of LightDM to get it done.
In the configuration file /etc/lightdm/lightdm.conf, append allow-guest=false as shown below.
Now restart the LightDM by issuing following command.
$ sudo service lightdm restart