Just stop. Your body is meant to have some amount of oil on your hair. It will be weird for the first weekish when you stop as your body will have to figure out it's new homeostasis (faggot) and it will get dry, oily, odd feeling for that short time. Afterward it will feel MUCH better than you've ever felt with shampoo. It will look much better too. Obviously if your hair actually gets dirty, you're a mechanic, firefighter whatever then use something to clean it but don't do it with shampoo. Because at the end of the day (((shampoo))).