Keep going around, probably a couple turns. You see the score or the cut is beginning to deepen. Keep going until the pipe separates itself. And it just pops off. After the pipe is cut, you may be left with some burrs.
Burrs are just small slivers of the copper that just kind of hang on.
That's what this spear is for. You just stick it inside the pipe, twist it a few times. And you'll see the burrs drop down . They're just little shards of copper. You can also use a wire brush that is made especially for this.