add deleteToken

[nvthuong1996]

add deleteToken method call when user logout

[iantearle]

I think you could handle your logout yourself and add:

// Remove FCM instance
FCM.deleteInstance()
  .then(() => alert(`Token deleted`))
  .catch((err) => console.log(err));

To delete the token.

[gladwelln1]

I've tried that and it doesn't seem to work.

Even after executing await FCM.deleteInstance() you still get the same token when executing await PushNotifications.register().