If you want to control what music employees have access to, you can limit the music available in the app. To do this, go to Account settings and turn on the toggle for Limit music selection in apps. This will apply to all zones on your account. It will hide Home and the possibility to add new music to the iOS, Android, and Sonos players. 
With the Windows player, you can't change the music from within the Windows app. The admin needs to log into the account here to change the music.