QAnon is a broad, baseless conspiracy theory about a "deep state" network powerful government, business and media personalities waging a secret war against Donald Trump.
A Facebook spokeswoman said the group was removed because it "repeatedly posted content that violated our policies."
Twitter banned thousands of accounts and said it would block QAnon URLs, while TikTok deleted all hashtag related to videos of the respective group.
The deleted Facebook group, called Official Q / QAnon, had almost 200.000 members.
However there are many other QAnon groups that are still active on the platform.
The fans of the group mainly support their president USA.
The Reuters states that the official group "exceeded the limits" regarding intimidation, harassment, hate speech and the exchange of possible harmful elements of misinformation. The FBI issued a warning last year about "domestic extremists based on conspiracy theories" and identified QAnon as a potential domestic extremist threat.