how to disable auto login in linux mint

Edit

/etc/mdm/mdm.conf

and set

AutomaticLoginEnable=false

Open 'Menu' > 'Login Window' to open the Login Window Preferences. Select the 'Security' tab > uncheck the 'Enable Automatic Login' option.

To me, disabling "Enable Automatic Login" in "Auto Login" tab from Login Window Preferences wasn't enough (login screen was showing up, but a moment later system was automatic logging me). I had to uncheck also "Enable Timed Login" from the same section.