Stammering cannot be completely cured and most people who say they have cured it are actually just trying to motivate others. It can’t be fully removed but with practice it can be managed. The same happened to me I used to stammer a lot. My mind would think too fast and send mixed signals to my mouth causing me to stutter. But after a lot of practice I learned how to control it. The stutter didn’t completely go away but I learned how to speak properly and manage it.