I've got a Marin Pine Mountain 1 2016 - it comes with a frame integrated bolt seatpost clamp. Is it possible to cut this off and use a QR seatpost clamp instead?
Seat Clamp :
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.