For Apple App Store subscriptions: If you don’t see a cancelation option but instead see resubscription options, as shown in the image below, then your subscription should already be canceled.
Additionally, if you do not see a subscription at all, you may be subscribed through Stripe.
For Google Play subscriptions: If you don’t see a cancelation option, but instead "Canceled" in red, as shown in the image below, then your subscription should already be canceled.