Speech therapy works in all kinds of ways, but stutterers will have to usually learn how to push past a block fluently. So yes, we are thinking about our speech while we speak, or at least when we reach a block that we have to overcome. Unlearning it would be to stop using your fluency method, but after many many years it would be hard to teach yourself to stop doing something that prevents pain - because stutters often cause pain in the throat, mouth, or lungs. You would have to condition yourself all over again to undo what you learned, and it would be a lot harder that time around because you're basically conditioning yourself to inflict pain and/or tension in your body. No one would ever undo their therapy. That being said, some stutterers simply lose it, which usually means it was only caused by something minor and probably didn't last very long to begin with. A lot of children stutter for a few years and then it goes away. Those type of people don't need therapy, they just lose the minor stutter. Those who are diagnosed and have it as a legitimate mental condition, cannot cure it unfortunately. I appreciate your questions!