I am an old customer of CreditEase Finance. I saw a post on the internet saying that paying a certain consulting fee can teach me the method of reducing or exempting certain interest principal, right?

I'm afraid it's not the way to teach you, but the high "consulting fee" to cheat you. The so-called method is to teach you to provide false information, which is illegal. Once verified, it will be severely punished by law and included in the credit investigation. Don't believe in the so-called routine. It's all swindlers who cheat you of your money, and finally ruin their own credit, which is subject to legal control.