Cancelling subscription

If you only see an option to re-subscribe, then you may not have an active subscription. See if this helps: https://support.apple.com/en-us/HT202039

Is auto-renewal already off? Does it say it will renew on a certain date or does it only say the subscription will end then? If you are not seeing an option to cancel then it probably means the automatic renewal has already been turned off and the current subscription is simply waiting to expire.