Bike comes with frame integrated bolt seatpost clamp - can I cut it off and use QR?
Yes it's possible to hacksaw the clamp bosses off and then file the seat tube round and smooth so that a quick release clamp would slip over it.

Before taking such drastic action - which will significant hurt the resale value of the bike if you care about that - perhaps try to find a QR lever and skewer that will work with the existing clamp bosses.