The legal process of giving up one’s citizenship
Under U.S. law, this can be done only by a U.S. citizen overseas before a U.S. Consul under oath. The person must first establish that he is doing so voluntarily and has a legal status in another country.
A person may not expatriate himself if it would render them stateless.
Right To Repatriate
Having gone through the Expatriation process, this does not foreclose his right to return to the United States. I this is the desire, they will need to go through the Repatriation process when returning to the United States.