Since there are no side plates, you will need to remove the trigger bow screws, lift the bow out of the inletting, then remove the butt plate or recoil pad and remove the thru stock bolt. It probably has a hex head bolt that will come out with a socket with extension and rachet. Not sure it its SAE or metric. Having not had a merkel in my hands, I'm not sure if any other screws need removing, but carful examination of the rifle should reveal that. Any screw that appears to go into the wood should be removed.
Bob