Decrease the smoothness of selected mesh objects by one level. You can only decrease
the smoothness of objects whose level of smoothness is 1 or higher. You cannot decrease
the smoothness level of objects that have been refined.

You can decrease the smoothness of multiple objects. If the selected objects have
different levels of smoothness, their respective levels are decreased by one. If the
selection set contains ineligible objects, those objects can be filtered out.