To deactivate Nomorobo on your iPhone, simply delete the app. *This will remove the app from your phone, but will not automatically cancel the subscription.
To cancel your Nomorobo subscription on an iPhone:
1. Go to Settings > Tunes & App Store.
2. Tap your Apple ID at the top of the screen.
3. Tap View Apple ID. You might need to sign in or use Touch ID.
4. Under Subscriptions, Tap Manage.
5. Tap the subscription that you want to manage. In this case, Nomorobo.
6. Tap Cancel Subscription.
-For more information please check out Apple's Support Page by clicking HERE
Important: Uninstalling an app will not automatically stop your subscription. You must cancel your subscription to end your subscription. If you uninstall the app without canceling your subscription, you will still be charged.