IPA: /dɪˈproʊɡræmər/
KK: /dɪˈproʊɡræmər/
A person who helps someone to stop following a particular belief or ideology, often used in the context of helping individuals leave cults or extreme groups.
The deprogrammer worked tirelessly to help the young man regain his independence from the cult.
Deprogrammer → It is formed from "de-" (meaning to remove or reverse) and "programmer" (from "program" which comes from Greek "programma", meaning a written public notice or a plan). The word "deprogrammer" refers to someone who removes or reverses a previously established program or conditioning.
Think of 'removing' ('de-') a 'plan' or 'program' — that's what a deprogrammer does.