How to remove all subdomains of a site from Yandex and Google search results, and prohibit indexing subdomains in the future?

Question

Google

Question 1. There is a domain on which the main site hangs - for example. example.com
domain has dozens of subdomains - like sub1.example.com, sub2.example.com ... subN.example.com
Is there any way to remove all subdomains from search results without resorting to the standard procedure for each of them - adding to Yandex.Webmaster and Google. Webmaster, confirmation, manually entering the URL to delete... just a huge number of them, there would be a lot of manual work.
Adding the same robots.txt to each subdomain with

User-agent: *
Disallow: /

won't it by itself remove them from the search results if they're already indexed?
Question 2. Is there a way to prevent indexing of any subdomains of the main domain (for example, some directive in the robots.txt of the main one)?

Answer 1

https://support.google.com/webmasters/answer/93710...
crashes instantly, so you get tired of returning back