I would attempt the gold colored diamond paint removal disk. But if it is failed in that it never fully hardened, the blue wheel for thermoplastic materials may work better.
I would peel or scrape off as much as possible first. Maybe get some water underneath it to get it to detach. Sand off whatever is left.
Not a fan of sanding that epoxy crap. Watch your sander speed. That stuff tends to get gummy if speed is too high and it gets hot.
