Ubuntu MATE took over start up

I was trying out different desktop environments on Ubuntu 16.04 LTS and ran sudo apt install ubuntu-mate-desktop. It worked, but when I restarted my computer Ubuntu MATE took over start up and the login screen. After uninstalling ubuntu-mate-desktop nothing changed, so I ran sudo apt purge --auto-remove mate* and sudo apt purge --auto-remove *mate*. Now there is no loading screen when shutting down or starting up, and the login still has the layout from Ubuntu MATE.

How can I revert the start up and login back to Ubuntu default?