----- add to /etc/lightdm/lightdm.conf
[SeatDefaults]
autologin-session=true
autologin-user=root
autologin-user-timeout=1
user-session=LXDE
session-wrapper=/etc/X11/Xsession
greeter-session=lightdm-gtk-greeter
greeter-hide-users=false

[Seat:*]
autologin-session=true
autologin-user=root
autologin-user-timeout=1
user-session=LXDE
session-wrapper=/etc/X11/Xsession
greeter-session=lightdm-gtk-greeter
greeter-hide-users=false


----- comment in  /etc/pam.d/lightdm-autologin
#-- auth      required pam_succeed_if.so user != root quiet_success