In a recent update, Blizzard has included the mobile Authenticator as part of the iOS version of the Battle.net mobile app. With this change, players using the Battle.Net app on iOS may choose to remove the old Authenticator app from their Apple devices as long as they have synced their Authenticator credentials with the Battle.net app.
This feature update doesn't seem to be available for Android users at the moment, as the update is only at the iOS store.
The Battle.net Authenticator has a new home! The Authenticator is now part of the Battle.net mobile app. Log in to migrate your existing Authenticator with just a few taps — once you're set up, you'll be safe to uninstall the old Authenticator app.. Read more on wowhead.com