Replacing walls

[Opti]

I don't know if I am just mentally challenged and there is an option, but when caving and building underground it would be nice to be able to replace the walls/smooth them or be able to stack mine and place walls on the same tile.

[Sleipnir]

That's been a common request. Definitely on the list of things to add. :)

[Expirium]

Is this a feature yet? Ive built a floor that Id like to replace and I honestly dont know how without tearing all of the stories down.