I've just installed a dg unit in a wooden window frame and sealed around the edges with some clear silicon. Although I masked up to avoid it getting everywhere, on one edge the silicon spread past the masking tape onto the glass. I cleaned off most of it at the time but there is still quite a bit of residue left, which obviously looks awful on a window.

 

What's the best product to safely remove the silicon? I've heard that WD40 works and possibly IPA. My worry is that the glass is softcoat so I cant use anything abrasive.

If you let the silicone go off properly it will rub off glass. Other than that, Multisolve will remove the residue with a couple of baby wipes too. 
 

The coatings should also be on the inside surface not the external surface of the glass so you shouldn’t cause any damage cleaning it off