To remove hardened epoxy from metal, start by softening it with a heat gun. Then, use a scraper to gently remove the softened epoxy. For stubborn epoxy, apply a solvent specifically designed for epoxy removal and let it sit for the recommended time before scraping. If the epoxy is still not coming off, try using a rotary tool with a carbide bit to grind it away. Always wear protective gear and ensure proper ventilation when working with solvents or heat.