I will not talk about the other methods for stopping subvocalization, only the method I have developed myself. This method I developed was specific to my person, but thought that someone else might be able to make use of the information inside.
So why stop subvocalization? Not only can you read faster, but you are not as easy to have your mind read. Sub-vocalization slow down the reading process, and allows people to read your mind. And after reading this article, you should learn how subvocalization slows down the thinking process.
I found out that I was repeating myself many times inside my mind. Every-time I would repeat myself I would get louder each time. This was just before subvocalization process, or speaking to another person. First I would have the thought. Next I would translate that thought a few words. Then I would turn it into a English paragraph or sentience. Next I would then make it really loud. Coming after that I might speak it verbally. This different stages of the subvocalization makes me think slower, and loudly. I learned with concentration, that I can think just as clear and easy with only one thought processing, rather than repeating it. It takes metal exercise but can be achieved.
The basic idea is to think only one time. Never repeat yourself in anything you do, even if someone asks you to say it twice. Remember in school, one of the evil things that where programmed into children, was to make them loud by repeating them-self over and over again. This was done on purpose to make the population easy to read, so they can never keep a secret, making them naked in everyone's eyes.