Best, fastest and easiest way to clean is wipe grates with a ball of foil after each cook or if you forget then no worries, do it as it’s coming up to temp in your next cook.
As for the pit itself, a cycle of all vents open and let it go will burn everything off, simply let it go up, stay there for ~15mins and then slowly bring it down (shutting vents at 1000 degrees can have fireball consequences) and when cooler but warm, get your ball of foil to wipe off any cremated residue which will be like dust and not gooey nor greasy.
The more you use the less you “clean” but every now and then a heat cycle clean is good maintenance and if after a period of use, you get mold then no difference, just heat cycle and you’re good to go.
I would discourage the soap and water approach as the soap can leave residue and the water can damage.