How to set LightDM and XFCE to only start when I want them and not at boot
I'd like to keep XCFE for VERY occasional use, so when I'm not using it I'd like to quit it. Also I don't want it to start at boot. I've found a bunch of ways of uninstalling it but that's not what I'm after, I just want to make sure it is not running unless I start it.
To stop the lightdm from starting, you should be able to disable it by this command:
sudo systemctl disable lightdm
If XFCE still starts automatically, then check your .bash_profile. If there is a line like:
exec startxfce4
then put a # in front of it. Once that is done, you can start XFCE any time by typing exec startxfce4 at the command line. When in XFCE, if you log out it should put you back to your command prompt.