subscriptions remove

Stopping the auto-renewal will only stop it from auto-renewing again, it doesn't cancel what you owe iTunes for the current subscription period.

You will either have to pay what you owe, or try contacting iTunes Support and see if they will cancel the purchase as a one-off (purchases are considered final) : http://reportaproblem.apple.com or http://www.apple.com/support/itunes/ww

What options are you seeing for it : View, change, or cancel your subscriptions - Apple Support ? If it says that it will expire and is only giving you options to resubscribe you've already cancelled it - and you can't remove old subscriptions from that screen.