This is how I recovered:
1) Turn on the phone and connect it to your PC/laptop
2) While phone bootloops, open un command prompt on pc and type, one line at the time, but be quick to do that between bootloops:
This will reboot phone in recovery mode.
3) From there, delete data and cache, and reboot
4) You're done! You will also be completely unrooted, even to that LG software which monitors root