Login screen missing - Mate 16.04

[lah7]

There definitely is some configuration that is set to always auto login in to the desktop.

This post touches upon @wizd3m's suggestion:

Disable auto login

Open a terminal. sudo nano /etc/lightdm/lightdm.conf It displays some text as follows: [SeatDefaults] greeter-session=lightdm-gtk-greeter user-session=mate autologin-user=username Solution This would be your particular user name that is automatically logged in with or without password. Delete this username and type in the administrative username or leave it blank. Shut down the system. It will go back to the login selection screen. Just power down the system and put it on again.