By hand, with a brush and a rag, using regular car wash soap in a bucket of hot water. Take your time, there’s no hurry. Rinse well. Wipe it clean and dry. Then wipe it down with 303 spray, or the like.
I try very hard to keep the entire TJ that clean, and in perfect working order. I keep all the receipts for the next owner, which I hope I never meet.