If you have an active subscription, you'll want to remove the subscription.
To manage your subscription:
Tap on your avatar
Tap on the icon in the top left
Tap on Manage Subscription
This will bring up your Apple Subscription page. Any active subscriptions will be listed, and can be cancelled through here.
Here's how to delete your Onlife account.
Open the Onlife App
Tap on your avatar
Tap on the icon in the top left
Tap on Account
Tap on Delete Account
On the confirmation screen, tap Delete Account