A Sydney psychiatrist who posted "bizarre" alt-right conspiracy theories he claimed were the directives of US President Donald Trump to his practice's official website has been struck off the medical register.

Dee Why doctor Russell Everard McGregor claimed Trump had taped evidence of a global Satanist paedophile network, that 9/11 was faked, and that the ABC is part of an international deep state network covering up the crimes of the elite.

Russell Everard McGregor has been struck off the medical register. Credit:Jim Rice

Many of the 300-plus posts from 2018 onwards related to the debunked QAnon conspiracy that suggests Mr Trump is leading a crusade against "deep state" forces who protect satanic paedophile rings.

"Fight with your keyboard, knowledge and pen," McGregor wrote in one post in January 2018.