Disregard. I figured it out.

Noob here. I create a circle and extrude it into a cylinder. When I drag the cylinder away, the original circle (or a copy of it) remains behind. If I delete this circle, the cylinder gets deleted, too. This behavior is counter-intuitive to me, so maybe I'm doing something wrong. I'd like to not have the extra circle at all, but if it's unavoidable, how can I break the link between it and the cylinder so I can delete the circle without deleting the cylinder? Thanks.