/etc/systemd/system/autologin@service
...
ExecStart=-/sbin/agetty --autologin <username> --noclear %I $TERM
...
Disable:
ln -fs /lib/systemd/system/getty@.service \
/etc/systemd/system/getty.target.wants/getty@tty1.service
Enable:
ln -fs /etc/systemd/system/autologin@.service \
/etc/systemd/system/getty.target.wants/getty@tty1.service
Enable/Disable taken from: http://raspberrypi.stackexchange.com/a/38203