How do I remove tape residue from cured epoxy without damaging it?

Use denatured alcohol or isopropyl alcohol. Either one will help remove the sticky residue that tape leaves behind on cured epoxy without harming the epoxy itself.

You can also use a heat gun and a scraper: the heat softens the adhesive so it can be scraped off the surface.

Avoid strong chemical strippers for this job. Products like Klean Strip Premium Stripper are aggressive enough to damage the surface they're used on, and that's exactly what you're trying to protect when all you need to remove is a few bits of adhesive left behind when you pulled the tape off your dams or edges.