People discovery is a set of features that lets users to get information about people in the organization and to get links to the documents that they have authored. Disabling people discovery is not a common practice that should be performed, however there are certain situations in which disabling people discovery makes sense. You should only disable people discovery in specific cases, for example, in an educational environment where you may want to prevent certain students from being discovered in other schools or a teacher from seeing students in other schools not within your district.
The Plan to disable people discovery in OneDrive for Business and SharePoint Online article discusses people discovery, the options available to disable the functionality, and the outcomes.
There are several elements to consider in order to disable people discovery functionality:
You use the People Picker control to find and select people, groups, and claims when a site, list, or library owner assigns permissions in SharePoint. The People Picker control provides a "friendly" display of users or groups when a claim authentication is used.
A global tenant administrator can now disable the people search functionality used in the People Picker. The "friendly" display can be disabled by using the SearchResolveExactEmailOrUPN parameter of the Set-SPOTenant cmdlet.
The result of disabling the functionality is that in order to resolve a name in People Picker, you must type in a user’s full email address or user principal name (UPN).
You should consider how you want search to display in your environment. By disabling people search you are removing all instances of displaying a user profile in a search result set. For more on disabling people search, see Manage query rules. People search is controlled by the result source Local People Results (System).
Even after people search has been disabled, the presence of people's information still may exist on documents on OneDrive for Business or other assets. If this is not acceptable, then you can disable search completely by modifying all search result pages with a message such as "Search has been disabled" for the following pages:
Office Delve is powered by the Office graph and shows users the most relevant content based on who they work with and what they’re working on.
By disabling Delve, you will hide people and documents from being displayed that use Office Graph. For additional information about Delve, including how to disable it, see Office Delve for Office 365 admins
A user profile is the collection of user properties—and the policies and settings associated with each of those properties—that describe a single user. User profiles are important, because they help people find content that connects them with other people, learn more about each other; and collaborate using social features.
Examples of user profile information would include the following:
Hover over the “Modified By” property in a document library which displays a person's contact card with their data.
Entries like job title, department and phone number on a profile page.
To hide user profile information you can either disable settings from the user profile page or exclude sensitive profile information from the directory.
For information about how to edit the user profile page, see Add and edit user profile properties.