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.