Turn off the grill and allow it to cool.
Remove the grates and place them on a flat surface covered with newspaper. Spray both sides of the grates thoroughly with oven cleaner.
Place the grill grates in a plastic bag and twist up the top. Discard the newspapers. Allow the grates to sit for one hour.
Open the bag and remove the grates. Avoid inhaling the fumes when you open the bag.
Rinse the grates in the sink with warm water.
Wash the grates with a sponge and 1 tsp. dish detergent.
Rinse the grates thoroughly with warm water and dry them with a towel.
Set the grates into place on the grill.