To debunk an idea is to take it apart in public and show that it does not stand up — that the story, the “fact,” or the belief is false or wildly overblown. Journalists, scientists, and internet writers debunk myths, rumours, and miracle cures. The word is not as stiff as disprove, and it often has a slightly sharp, even cheeky feel: look, this famous claim is bunk (nonsense). It came into English only in 1923. You mainly debunk claims, myths, and theories. People do say an article debunked him, meaning it tore down his image, but that stretch is a bit rough; the tidy use is about ideas, not about destroying a person.