How to make a pdf file non-indexable?

Question

Search Engine Optimization

It is necessary to remove several PDF files from Google and Yandex.

Answer 1

1. write the corresponding rule in robots.txt
2. write nofollow in links to files
3. remove from sitemap.xml, if they are there.
4. in htaccess you can write this:

<FilesMatch "\.pdf$">
  header set x-robots-tag: noindex
</FilesMatch>

Answer 2

Should I remove all PDFs from the search results? Then add to robots.txt
Well, through the tools in the webmasters' offices, check by url, after adding this rule, is the file indexed?