The hypnotists part is to offer suggestions to the subconscious mind that will bring about the results that the client desires, and to do so in a safe, caring, confidential manner. Any one with an IQ of 70 or better can be hypnotized, if they are willing to follow instructions and have no unanswered fears about the process. There is no danger of a person failing to come out of the hypnotic state. In fact, if the therapist left the office or even died, all that would happen is the client would drift off into a natural state of sleep and wake up after he was rested. When you are hypnotized, you are aware of all suggestions given to you, and will not do anything you are opposed to doing.
All hypnosis is self hypnosis and the therapist has no power or control over anyone.
If I suggest something you dislike, disagree with doing or do not want to talk about, you won't do it. You will ignore my suggestion or come out of the hypnotic state. I can only help my clients to achieve their goals and only then if the motive to change is their own. From birth until about age 12 the critical factor of the conscious mind is not fully developed. The critical factor is that part of our minds that filters all incoming information for content and decides how it will be programmed into the mind.