Here are the quick steps to help you cancel your subscriptions.
Step 1: Login to your ecommerce account and click on Manage subscriptions.
Step 2: Choose the subscription that you would like to do changes to, and then click on "Manage your Subscription" in the Customer subscription detail page. Quick look of the screens below
Step 3: Now, scroll on the bottom of the screen for the subscription id you want to cancel and add your reason for cancellation to help the brand.
Quick Tip: Add an informative cancellation reason to help the brand understand the issue behind and improvise :)