I am sorry to bring this up and I know the solution is somewhere but I can't find it.
I drew a deck then added a circular stair. The stair attached itself to the deck and now the stair can't be moved without moving the deck. There is no easy to recognize option in the menu to detach the two items from each other. I wouldn't mind an intuitive way to separate these two items from each other. After all they were separately drawn.