Side windows:
When I did mine on my Paseo, I removed the door panels, and used lots of Windex and razor blades. The film peeled off, but left the adhesive. I sprayed that with Windex, let it sit for 20 seconds or so. The Windex would turn the adhesive into a gummy mess. Multiple hits with Windex and razor blade, with paper towels to wipe, finally cleared it off. I left the door panels off for the tint install also, so that he could tint well below the door panel edge, and to avoid any problems or dirt from trying to tint behind the door panel top edge.
Rear window with defroster lines:
I had my tint installer remove it. I was going to do it, but he said that he could not guarantee his work if I did it, due to whatever I did not completely remove. He used a steamer, with garbage bags to make an enclosed area. Search online for more info on that.