The website for "America's Frontline Doctors" was registered just 11 days ago, a web domain age checker revealed - and the site was taken down by Tuesday afternoon.
"Tea Party Patriots," a right-wing political group backed by wealthy Republicans, said on its website it was responsible for organising the Washington summit.
Further research on Immanuel's web page, now accessible only via an archived website viewer, as well as her YouTube account, reveal a long list of bizarre and unscientific beliefs.
These include that "tormenting spirits" routinely have "astral sex" with women, which in turn causes "gynecological problems, marital distress, miscarriages" and more.
In a 2015 video, Immanuel, who leads a religious group called Fire Power Ministries, said: "There are people ruling this nation that are not even human," describing them as "reptilian spirits" who are "half human, half ET."
In the same video she rails against the use of "alien DNA" to treat sick people, which she said had resulted in human beings mixing with demons.
Other targets of her anger include gay marriage, which she said would result in adults marrying children.
Immanuel was born in 1965, received her medical degree at the University of Calabar in Nigeria, and has a valid physician's license, according to the website of the Texas Medical Board.
After Facebook took down the clip, Immanuel warned that the company's servers would start crashing until it was restored.
"If my page is not back up face book will be down in Jesus name," she tweeted.