While taking out a bathtub I discovered a vent for the toilet. Looks like it runs straight up to an attic space (not a sealed space, outside air passes through at will) and not through the roof to the outside. The wall that it is in is perpendicular to the main wall to the room and I would like to reduce this wall to a half wall. My question is: does the vent have to go straight up, or can I put a 90 degree bend and reroute it to another attic (sealed space) behind the main wall of this room. And, is there a minimum height for the vent that I have to watch out for. There is also a main vent for the bathroom and laundry about 9 feet from (downstream) this newly discovered toilet vent.