Hi I would like to know if I could move this drain waste vent, it comes up through the floor and out the roof I was wondering if I could move it into the wall right behind it?

 

One has to wonder why it isn't inside the wall in the first place. Stacks like that usually need to be in interior walls (not exterior walls) if you live in a cold climate. And the wall would have to be a minimum 2x6 wall for it to even fit. And the amount of demolition and repair to get it into the wall might cost more than you are willing to spend. But when money is no object, most anything is "possible".

 

Could I reduce the pipe to a 2” or even make a hole through the bottom framing 2x4 since it’s a none load bearing wall?

 

With no info to base an answer on its pretty hard to say.

 

If it's just a vent without a bathroom above, yes it can be moved. Most likely, it needs to remain 3" - pipes are rarely oversized, so I wouldn't assume you can decrease the size.

From a plumbing perspective, vent pipes can be moved and routed in lots of different ways. But as others have said, there's probably a reason it isn't in that wall. It'll take some work, but it can be moved by cutting it all out, and putting it all back together.

If there's an attic, you could probably elbow it back to the existing roof location - otherwise it'll need some roofing work too to patch the old hole and properly flash the new vent pipe.