You can sell units that are placed on buildings (e.g. Service Depot, Helipad, Airfield) by positioning your cursor over the unit with sell mode on clicking when the yellow sell cursor is shown (mos of the time around the edges of the unit).
To reproduce buy a Service depot and try selling an Aircraft on it.
You can sell units that are placed on buildings (e.g. Service Depot, Helipad, Airfield) by positioning your cursor over the unit with sell mode on clicking when the yellow sell cursor is shown (mos of the time around the edges of the unit).
To reproduce buy a Service depot and try selling an Aircraft on it.