How to remove a subdomain from the index?

Question

Search engines

The webmaster has an error:

The search results found subdomains of the site - https://egor.icy.moy-site.ru

I can’t remove it from indexing, I created the egor.icy.moy-site.ru folder, threw the robots.txt file there, here is the content:

User-agent: *
Disallow: /

But it does not remove from the index. What's wrong?
HTTP status code 404 Not Found.

Answer 1

turn it off or rename it
will disappear almost instantly