Some older Atria-branded apps are discontinued or merged into larger platforms (e.g., ACT Fibernet absorbed Atria TV into its main app). If the app no longer exists on your phone:
for any unique notice periods or terms that might apply to your account. Check Your App Store Atria apps cancel subscription
Here is the step-by-step process to cancel on an iPhone or iPad: Some older Atria-branded apps are discontinued or merged