How to configure startup without passwords

[colina1234a]

I run an offline PC with V 4.2 and would like to configure it to just start me
up as root without passwords or loggin in etc and go straight to desktop
when I switch on.

I found the KDE option to boot without passwords but that is buggy
(seems impossible to turn off again) and doesnt appear to work as root.

I recognise that doing this is unusual but I'm guessing it must
be possible - can anyone help please?

PS - if I can get it to shut down without "logging out" that would help too.

thanks