But Honey, if you dont tell him why, he wont know. He will just keep doing it to other people. You dont have to be rude or confrontational. Just stay calm, and collected.
Even if you have to call him, just say something like " Hi, Mr. whoever you are, I am sorry to inform you that I will not be participating in your lessons anymore. I felt that you were not the right teacher for me. I need someone less frustrated, and more understanding. I am sorry if this causes any trouble. Thank you for your time" and then hang up You could even type a letter and drop it by if you had too.
It is alot more grown up to talk about it, then to just say I am not going back. You will help others by taling it through with him