to clear a room you mine this leaves a floor and ceiling.
For stairs up/down stairs allow you to go up or down from the layer they are on. This requires stairs on the layer you are moving to as well. Down stairs go only down up stairs go only up.
To remove the floor from a layer you would use channel, this leaves a ramp on the lower layer that allows movement up and down. These can be removed.
@lightnsfw thank you!! So far I’m at the tutorial stage and couldn’t get the stairs placed or any digging done form the mining menu. I tried several new games to see if that was the problem but I think it user error.