The fact is: you don't control the Google index, Google does.
Give it time and the crawlers will only go to a page and get
404 so many times before they drop it form SERPs.
Though I have found that they can remain indexed for some considerable time, with
404s for long gone pages still appearing in Search Console. This suggests that they may remain in the index and crawlers may occasionally look, but the important thing is they are gone from SERPs.
You may want to set up
301 redirects for equivalent pages or
410 headers to say it's gone in htaccess.
Too late now, but a tip for future projects. If you have a site in development on-line, you may want to use
robots.txt or the robots metatag to keep the pages out of indexes during development.