As Google says on their support page:
Google will remove the snippet and cached copy from search results. If
the page is no longer available , it will remove the search result
entirely. If the page is still available , it will remove the
currently cached version and snippet from search results.
Because the webmaster has redirected the URLs to other posts, the Google Remove Outdated Content Tool will only remove cached content because the URL is redirecting another post. This may take a few days to complete.
To review the exact steps that you need to take to remove an outdated page description or cache I have included it below:
Follow the instructions below if the short description of the page in
search results (the snippet) or the cached version of the page is out
Go to the Remove outdated content page.
In the "Enter URL of outdated content" box, paste the URL of the page. (Learn how to find the URL of the page)
Click Request removal.
If you see “Has the site owner updated or removed the content,” select Yes.
Select The snippet and cache are outdated.
Explain exactly what is outdated about the snippet or page. In this box, enter in a word that is on the old version of the page from
Google’s search results that is not on the current version of the
page. For example, the cached page might show your name, which isn’t
in the new version. In this case, don’t write "my name has been
removed," but instead type your name as it appears in the cached
Click Request Removal.
Still seeing the offending content?
If this still doesn't have the desired effect, ask the webmaster to remove the redirect to the new post, so that the old URL returns a "Page Not found" error. In my experience this method is the most sure, and usually removes the URL and all the page content within a few days at most.