There are some things to be aware of when deleting certain apps:
Even if you delete the Contacts app, all of your contact information will be available from the Phone app.
You can still make and receive FaceTime calls in Contacts and the Phone app after deleting the FaceTime app.
Removing iBooks, Maps, Music, or Podcast apps will make then unavailable to use with CarPlay.
You will have to unpair your Apple Watch before deleting the Watch app.
Deleting the apps is simple:
Touch and hold the app until it jiggles.
Tap the X that appears on the top-right of the icon, then tap Remove.
Press the Home button to finish.
If you want to get an app back, here's what you do:
Fire up the App Store app and search for the app.
Tap Download to restore the app.
The app will now download back to your Home screen.
With all that out of the way, here's a selection of third-party apps that you can download to replace the built-in app or just to make your iPhone a little more awesome.
Built-in iOS apps you should replace with third-party apps