removing the mod does not remove surface.
not a big issue but would be nice to have a way to clean up after it

unfortunately that's just not possible, mods have no "after i get removed, delete this" code

supposedly surfaces associated with a planet do vanish, but that was only pointed out to me recently (and after this mod was released), i have yet to research that "surface autodelete tech"

you could in worst case make a mod to "clean up"

You can run the command game.delete_surface('awesome-sink') to manually delete the surface after removing the mod

or with the /editor, but it's not convenient since both would disable achievements, i have yet to look into the planet trick

done