If your subscription is not listed in your subscriptions overview, then that subscription doesn’t exist on that Apple ID account. If you have multiple Apple ID accounts (not advised), then check for each.
If your subscription is listed in your subscriptions overview, then you can cancel it there.
If it is already canceled, then the Cancel link or button will be replaced by re-subscribe options. That signifies that it was already canceled.
Canceled subscription during the paying periods stay active until the end of the current billing period. Canceled subscription during the trial period will expire immediately.
If you want to cancel a subscription through Apple, then you should do so at least 24 hours before the renewal moment.
To cancel, do any one of these:
- On any of your Apple devices: How to cancel a subscription from Apple - Apple Support
- On the web: How to cancel Apple TV+ - Apple Support
- On third party devices with the Apple TV app: Manage subscriptions in the Apple TV app - Apple Support
- On a PC with iTunes: Use a Windows PC to cancel subscriptions from Apple - Apple Support
If you need further assistance, contact Apple for support and service (phone numbers) or start your support request online (chat/email/callback). Authentication might make that less easy that doing it yourself.