Office 365 Hide Documents from Delve

This is something that a few clients have asked us about recently and i always point them towards the Microsoft Support Website and also teach them about Permissions. Below is the steps required to hide a Document completely from Delve. If you don’t want a document to show up in Delve, you can create a HideFromDelve site column of the type Yes/No. This site column creates a new crawled property, ows_HideFromDelve, which is automatically mapped to the HideFromDelve managed property.

Add a site column to the library or list where the document is stored

1. Log in as a site collection administrator and go to the site where the document that you want to hide from Delve is stored.
2. On the ribbon, click the List or Library tab.
3. Click Create Column in the Manage Views group and Type HideFromDelve in the Column name box under the Name and Type section, and then select Yes/No (check box).IMPORTANT: Click No in the Default value dropdown menu in the Additional Column Settings section. If you select Yes, all new documents will be hidden from Delve.
4. Do one of the following:
   • For SharePoint 2016 or SharePoint Online, uncheck the Add to all content types checkbox.
   • For SharePoint 2013, uncheck the Add to default view checkbox.
5. Click OK.

Mark the document you want to hide from Delve

1. Go to the site where the document that you want to hide from Delve is stored.
2. Find the document that you want to hide in the library or list, click edit properties and then check HideFromDelve.
3. Click OK.

After the next scheduled crawl, or after you request re-indexing of a document library or list, the document is hidden from Delve. If you want the document to show up in Delve again, uncheck the HideFromDelve column for the hidden document.

Reference: https://support.office.com/en-gb/article/Manage-the-search-schema-in-SharePoint-Online-d4fab46d-ba41-4c03-9d4c-32b5b33198b6