Looking at the schematic I’d try taking your output from volume lug 2 leaving everything after vol 2 the boost section off the board
Don’t solder vol 2 to the pcb just put a wire from it to the out jack tip I’d imagine you may lose volume without the boost
Easy enough to try and see how it sounds if it doesn’t sound good populate the boost section
If you simply want to omit the extra switch you’d need to connect vol 2 and R16 continuity check to see where vol 2 and R16 are connected to the switch pads if they connect to different SW1 pads jumper them