Here’s a simple, but very effective way to clean the cooking grates on a barbecue grill. Pour white vinegar into a clean spray bottle and spray the cooking surface. Allow the vinegar to remain on the surface for a few minutes.
Then, tear off a good-size piece of aluminum foil, crumble it up into a ball, and scrub the cooking surface with the aluminum foil. The acid in the vinegar cuts through grease and grime and the foil acts as an abrasive to remove stuck-on bits of food. BTW, this works best while the grill is still warm, but so hot that you might burn yourself.