When clearing outdated search results, your approach depends on site ownership....

https://www.ready-bookmarks.win/when-your-search-results-are-cluttered-with-old-irrelevant-pages-the-fix

When clearing outdated search results, your approach depends on site ownership. If you own the site, delete the content and ensure it returns a proper 404 status; don't rely on "soft" errors that keep pages indexed