In this short tutorial, I'll show you how to hide the Guest Session from the LightDM login screen on Ubuntu. This is something that I do every time I install a fresh copy of Ubuntu. Hopefully, there will be a button for that in the future.
Edit /etc/lightdm/lightdm.conf
:
$ sudo nano /etc/lightdm/lightdm.conf
Insert this line:
allow-guest=false
Just restart Ubuntu for changes to take effect.