Temporary hiding vs permanent removal
Temporary: the Removals tool
For quick removals, Google points owners to the Removals tool, which can take a page on their site out of Google's results within a day.
A Removals tool request is temporary and lasts about six months.
A temporary removal hides the URL from Search results but does not stop Google from crawling the page.
The Removals tool affects only Google Search; it does not remove content from the internet or from other search engines.
Permanent: change the page itself
For a permanent block from Google Search, Google lists removing or updating the page content first, ahead of password protection and noindex. To make a removal permanent, Google says to remove or update the content and make the server return 404 (Not Found) or 410 (Gone). For Google, either code works: it currently handles 410 and 404 alike.
noindex comes last on that list, and it has two catches. The page only drops out after Googlebot recrawls it, and for low-priority pages that can take months. Google also rates noindex as weaker than deletion or a password, since people and other search engines can still open the page.
Accidental deindexing after a launch or template change
Google says a drop in indexed pages without more errors can mean the site is blocking pages via robots.txt, noindex or a required login. After a launch, look first for a rule left over from the build. In a site move, Google's checklist says to lift the noindex rules added to the new site once the redirects are live. For the redirect and indexing steps of a domain move, see domain migration without losing SEO.
Server trouble causes a slower drop. URLs that keep returning server errors (5xx) are eventually dropped from Google's index, even though they are kept at first.
Google says not to use robots.txt to remove a page from Search results. A robots.txt block hides the noindex rule from the crawler, and the page can stay in results.
Why Pagepro baselines Search Console before a switch
Pagepro records Google Search Console data from the old site before the switch, for example on a WordPress migration. With that baseline, a before/after comparison answers one question honestly: did pages drop out after launch?
Sources
- How HTTP status codes, and network and DNS errors affect Google SearchGoogle · developers.google.com
- Block Search Indexing with noindexGoogle · developers.google.com
- Manual Actions report - Search Console HelpGoogle · support.google.com
- Remove Your Site Info from GoogleGoogle · developers.google.com
- Removals and SafeSearch reports tool - Search Console HelpGoogle · support.google.com
- 404 (Page Not Found) errors - Search Console HelpGoogle · support.google.com
- Page indexing report - Search Console HelpGoogle · support.google.com
- Site Moves and MigrationsGoogle · developers.google.com