Support left overs

New to the world of 3D printing. love my X1C so far only issues i have had have been either self induced or importing a .stl from another site like thingaverse.

So i printed an item that needed support structure. no biggie did this and all was good. until i removed the supports from the print, there is rough surface on the print where the support was attached.

what does everyone use to clean this up?
heat gun?
sand paper?

thanks for your knowledge.