Is diagnosed psychosis (non-drug induced) permanent? Or can it go away?
It depends on the situation.
Psychosis is a severe mental disorder in which thought and emotions are so impaired that contact is lost with external reality. There are many known causes of it. Psychosis can be induced either socially (environmental factors), abuse of drugs, and genetically. You can refer here for an explanation of its causes.
So generally, there is no cure and it is permanent. But in some cases where psychosis develops from outside conditions (socially caused), and those situations can be addressed, the victim (together with a professional psychiatrist) can then control their unusual behaviour along with some medications (which can inhibit some of the symptoms).
Hope this helps! :-)