If you have an employee who requires not be found in Engage, your System Administrator can opt-out of the employee from Engage's search. If you want to update multiple people, then use the Bulk Update Person or the Person Import and populate the Opt-out of Engage column.
Remember if you are a System Administrator who has the secured action Reservations - See opt out of search users then you will be able to see everyone (including opt-out employees). If you want to complete a test then sign in with your test user who does not have the secured action.