Without anything to rub or effort, Put the oven rack in a bag

What You’ll Need:
Large plastic garbage bag (or sealable trash bag)

½ cup ammonia

Gloves (recommended for safety)

Well-ventilated area (like outdoors or in a garage)

Steps:
Place the oven rack in the bag
Carefully slide your oven rack into the plastic garbage bag.

Add ammonia
Pour about ½ cup of ammonia into the bag — you don't need to cover the rack completely. The fumes do the work.

Seal the bag
Tie or seal the bag tightly to trap the ammonia fumes inside.

Let it sit