If you'll allow me to dive into the psychology a bit, the root of a cult of personality is archetypal: the creation of an idealized persona that an ostensible leader must enter into and fulfill. A leader must appear in the world as (for lack of a better term) a kind of demigod, a larger-than-life human with superhuman capacities or characteristics, one who can single-handedly take on the problem of the salvation of others. The cult forms around the leader because people identify with him as the archetype of success. The sanitized, reified persona the leader projects becomes the ideal the followers reach for: his achievements are their achievements; his strength and wisdom are what they hope for themselves; his failings and weaknesses are their failings and weaknesses, and are instantly forgiven the way we all look past our own mistakes and misdeeds.
A cult of personality is over-identification tied to the hope of salvation: he is us, and we can rise out of our misery to find his kind of power and success if only we can follow his path.
Cults of personality are not intrinsically bad things. Most religions (Christianity, Judaism, Islam, Buddhism, Jainism, etc) began as the teachings of one semi-deified person to a cult of devoted followers, and those teachings can resonate through the world for thousands of years. But as we know, cults of personality can go very badly wrong...
Ending a cult of personality means destroying the archetype, which is far more difficult that it might seem on the surface. People create archetypes of salvation because they honestly feel they need to be saved from something, so until that 'something' is addressed these people will be vulnerable to cult mentality. This is aggravated by the fact that cult leaders of the worse sort are often quite skilled manipulators, and will aggravate the sense of urgency and depth of misery behind people's desire for salvation. With that in mind, there are really only two ways for a cult of personality to die out:
- The archetype of salvation must become irrelevant (usually by removing the problem it was meant to save people from), so that people are no longer inclined to seek it out, or...
- The leader presenting the archetypical persona must be rendered fully and completely human: weak, deluded, stupid, frightened, haughty, sinful, shamed, or anything that will cause people to cease to believe in the demigod-like puissance of the leader.
It isn't sufficient to trash-talk the archetype of the leader, which will be ignored by the cultists as an effort to defame the Great One. Somehow, one must slip past the presented persona and expose the man underneath. This is the reason, for instance, that Hitler never allowed recordings of his voice outside of public speeches and rallies; he did not want people to hear him speak in a normal, casual voice about trivial subjects because that would undercut the illusion of him as constantly fiery, dynamic, focused force of nature.