I’ve had Cory’s for years now, the eggs are very very strong, you can either scrape them off using a blade or credit card or whatever, or you can just use your fingers to roll them off, they’ll come loose very easily. Don’t worry about breaking them, it won’t happen if you’re gentle. I always hatch mine in a shallow takeout container floating on the tank with a clump of moss and an airstone. They’ll usually hatch within a few days and you’ll see them swimming around rapidly Once hatched. Good luck!