The page you're linking to does describe how to do that:
When you use a dash before a word or site, it excludes sites with that
info from your results. This is useful for words with multiple
meanings, like Jaguar the car brand and jaguar the animal. Examples:
jaguar speed -car or pandas -site:wikipedia.org
Do a video search for javascript -site:youtube.com
to exclude results from youtube.com.
Note the dash: If you searched for javascript site:youtube.com
you would restrict results to only videos from youtube.com. From the same documentation page:
site:
Get results from certain sites or domains. Example:
olympics site:nbc.com
To get results from multiple sites or domains,
combine with OR. Example: Olympics site:nbc.com OR site:.gov