How do you remove stuck retainer nut?

To remove a stuck retainer nut, first, ensure the area is clean and free from debris. Apply penetrating oil around the nut and let it sit for a few minutes to loosen rust or corrosion. Use a wrench or pliers for grip, and gently turn the nut counterclockwise. If it remains stuck, consider using heat from a heat gun or a blow torch to expand the metal slightly, which may help break the bond.