Well, tried burning hot water, and in 10 minutes only a corner came off, so time for plan B
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Removing the sunvisors is a piece of cake, so I started with that step. After removing the 2 visible T25 torx screws, wiggle the connector out of the hole, and pull on the connector closest to the roof of the car, not the sunvisor. Stick your fingernail where the 'hole' is (or insert a small screwdriver, but you'll dent the connector) and it'll come right out.
Took the 'Goof Off' route, which I've always used (and will always use); took all of 5 minutes to get it completely off... but the odor will remain. My solution was to first get a damp microfiber to remove most of the stuff, then spray 'Fabreze' a couple of times to neutralize the bad odor. After an hour of airing them out, they were ready to be reinstalled in the car. Much easier to remove sunvisors first folks. Hope this helps.