This wont happen immediately,
once indexed your post will appear in search results,
periodically search engines will attempt to reindex it.
If they get 404 – Not found response, they can remove your post from search results.
I understand. But even if appearing in search results, if someone clicks it, its content will not be visible anymore right?
If someone click it, they will be redirected to your site and will see a nice 404 – Not found page.
Also it seems you have asked (almost) same thing twice,
please continue in older topic: https://wordpress.org/support/topic/best-way-to-unnpublish/
closing this one.
