Remove search results
As a SharePoint Online administrator, you can temporarily remove items from search results with immediate effect. The items that you can remove can be documents, pages, or sites that you don't want users to see. An example of this could be a Word document containing an invitation to an event that has been cancelled, but the organizer has not removed the document from the site yet.
This is only a quick fix! Unless you delete the items or change the permissions of items manually, they will show up again in your search results after the next crawl.
Sign in to Office 365 as a global admin or SharePoint admin.
Select the app launcher icon in the upper-left and choose Admin to open the Office 365 admin center. (If you don't see the Admin tile, you don't have Office 365 administrator permissions in your organization.)
In the left pane, choose Admin centers > SharePoint.
On the search administration page, choose Remove Search Results.
On the Remove Search Results page, in the URLs to remove box, type the URLs that you want to remove from the search results. Type one URL on each line.
Click Remove Now. The URLs are immediately removed from your search results.