While it is no longer possible to sign up through iTunes / Apple App Store, there are still those that signed up through this method in the past.
In order to cancel your Hallmark eCard/Hallmark Movies Now subscription that was created on an iOS device, please follow this link while on your iPhone/iPad or you may follow the steps below.
To cancel your App Store subscriptions via your iPhone or iPad head to Settings > iTunes & App Stores.
1. Tap on your Apple ID at the top of the page. Note that you’ll need to make sure you’re logged in with the account associated with the subscription you wish to cancel. If you’re not, follow the next step but tap Sign Out instead. Then log back in with the correct Apple ID account.
2. If you’re logged in with the correct account, tap View Apple ID. Depending on your device’s security settings, you may need to authenticate with Touch ID, Face ID, or a passcode first.
3. Scroll down to find and select Subscriptions.
4. Find and select the subscription you wish to cancel from the list of your currently active subscriptions.
5. After selecting the desired subscription, tap Cancel Subscription at the bottom of the subscription’s info page.
6. Tap Confirm to verify your cancellation.
Unfortunately, if you are unable to cancel the subscription this way, it may be best to contact Apple/iTunes directly by visiting https://getsupport.apple.com/ or by calling 800-275-2273 for further assistance.