Electrolysis is the only method of permanent hair removal. It is a process in which a trained professional inserts a thin wire (probe) into the hair follicle, applies an electrical current, and destroys the root of the hair, so it no longer grows. This current kills it and causes the existing hair to release from the follicle. It is then removed with a pair of tweezers.
This treatment is a progressively permanent process which means it will take several treatments to completely eradicate the hair.