Is it possible to have panic disorder as a child and then it go away by the time you reach adulthood?

Panic. Very possible, depending on adjustment as grown-up. May reoccur under stress.
Face the problem. Yes. It is possible. Panic attacks are consequences of fear and heightened levels of anxiety. Symptoms will increase with stress, caffeine, etc. So, with time, if levels of stress are reduced, if coping skills improve, symptoms may remit spontaneously. More probably, however, symptoms will get worse if left untreated. See a psychologist. It is easier to treat if addressed sooner.