Firearms are a concept, not just an object. They exist now, you can’t make them not exist. Further, the basic principles behind firearms are shared with plenty of other things. If you want the entire concept to disappear, you’d have to take away A LOT of human knowledge and technology.
Its like asking how we’d go about…

Not really, i mean they had tens of thousands of years to do it. So it was probably more like, “Great great grand daddy decided to move the camp a few miles further south down the beach. Grand daddy decided to move us across to the other side of that river. I figured that green field just over that hill looked pretty…