Trying to deprogram a troon is like trying to cure someone's depression. A third party can't force it upon them, they have to realize they have a problem and want to fix it first. Just cut ties and move on, it's not your problem.
I'm something of an armchair therapist for friends (because I seem to attract the most unstable people) and I've found that the first big hurdle with helping anyone who is mentally ill is that you need a high degree of trust so the person won't just push you away over things he/she doesn't want to hear. However I wouldn't know how to approach helping a troon considering society is actively telling them what they're doing is good but to hazard a guess a way to go at it you'd do something similar to with an abuse victim by first getting them out of the influence of troons and apologists and then break down the flood wall of negative feelings they've built up behind a sort of unstable mental wall. Now in cases of abuse victims I've dealt with this way I couldn't stress the importance of basically babysitting them until they get through the worst of it and I really wouldn't say its worth wasting your time on an Internet troon you've never met
Take away their internet access. Makes it that much harder to attention whore. Most of them are too autistic to interact face to face with people, so they'll just hole up in their room and starve to death like God intended.