This should help https://www.hometalk.com/39076782/the-easy-way-to-clean-your-grill-before-grilling-season
Hi Scarlet: if the grids are gunky, this is what I use: I use is a paste of vinegar and cream of tartar (the dry stuff). Make a paste of vinegar and cream of tartar (use just a bit of vinegar at first as the cream of tartar sort of melts) and put it on the gunk. Maybe start out with 3 tablespoons of cream of tartar and a 1/2 teaspoon of vinegar. Add more of whatever to make a paste. Let it sit for about 15 or 20 seconds and then scrape off with a plastic putty knife or one of those plastic scrubbies. You may have to do it a couple of times if the gunk is thick, but usually not. There is no smell and it is environmentally safe. I've heard that using a metal brush for the grill is not good as sometimes the little metal bristles come off and stick to the grill and you don't see them. When you cook something, they may attach to the food and you ingest it and get really sick or injured. As for cleaning the outside get a pail of warm water with Dawn and maybe 1/2 cup of vinegar and scrub with a plastic bristle brush. For the inside, where the charcoal goes, scoop out all of the ick you can, and usethe vinegar/cream of tartar mix if it's really grimy. Otherwise, use the Dawn/vinegar/warm water thing. Rinse well and you should be good to go. Good luck.
Here is a video that will help: https://www.youtube.com/watch?v=xmIQVDvkvZs
My hubby has a propane smoker and the racks get filthy. I just put them in the bathtub after filling it with water and 1/2 cup of dawn. Let them soak overnight and rinse the next morning. It is amazing how clean they are afterwards (at least until he uses his smoker again)/