Enable Guest Logins Ubuntu 18.04 Bionic
From GroovixWiki
Regular non-Groovix Ubuntu 18.04 no longer offers guest logins by default. To enable guest logins:
apt install lightdm and be sure to choose lightdm as the default greeter
edit /usr/share/lightdm/lightdm.conf.d/50-disable-guest.conf to set allow-guest=true
and reboot
NOTE: CVE-2017-8900 https://bugs.launchpad.net/bugs/1663157