My 9 year old son won't let me help him to wash him when he bathes, he was dirt stuck on his skin around his forehead, behind ears, neck and some in his arms, what can I use to make all that dirt ease and go when he washes up? It's dark brown dirt!

A really good soap and maybe a bath scrub could do the trick. Tell him that if he won't let you help him - then he can not leave the tub until the dirt is gone. You could also get one of those little nail brushes so he can scrub his nails, hands and feet. Does he let you in the bathroom when he is cleaning? You could supervise and tell him that when he can start cleaning himself better - you won't have to do that.
Also, he could start showering instead of baths. This way some of those places are actually getting water on them when he cleans.
Hope this helps.

Let him bathe himself. He is old enough to do it himself. If he has no pride in his appearance let him get teased and se how it feels.. it will only take once and he will start to take better care of himself.

At this age, your son is most likely trying to show his independence and DOES NOT want you to be treating him like a "baby". He truly is old enough to be able to bathe himself (may daughter is 7 and she has been taking a shower all by herself since she was 6 - and she does an excellent job!! ). She also loves to take a long, soaking bath. In addition to the fact that he is most likely demanding independence, he may be complaining that when you wash him you are hurting his skin by trying to scrub the dirt off. Are you sometimes in a rush when you are trying to bathe him? This will definitely stress him out if you only allow 5 or so minutes to get the job done. If he has a lot of dried dirt/mud on him, a nice, long soak in a warm tub is best way to take care of the problem. This is similar to the idea of you soaking dishes when there is burnt or dried food on them. Maybe filling up the tub with bubble bath to make bubbles and making the experience more fun would also help. Wal-Mart also has a product that has tablets that fizz in the tub and turns the water different colors in warm water. My kids love this!! I have also bought foam for the tub that will allow the children to create artwork on the tile that is easily washed away with water. Make the experience fun and you won't be able to get him out of the tub!! When you go to the store, show him the different things that I mentioned above allow him to help pick out the items. Get him involved in the fun experience. Show him that keeping his body clean is not just a necessity, but a fun experience too!! Hope this helps.