Can I cancel my subscription at Apple store

You need to cancel the subscription. See the links below.

Purchases - View, change, or cancel your subscriptions.      *

Purchases - Subscriptions not billed through Apple    *

Link to contact Apple Support at the end of the article.

Purchases - the subscription that you want to cancel is not listed    

Only you can cancel it from one of your devices. Nobody else can cancel it for you.

What happens when you follow the steps in the support document you posted from? Are you having an issue?