Canceling a client's subscription product is pretty straight forward but it comes with a WARNING, once you cancel a client's subscription there is no turning back, we can't even help you salvage it...
Step 1: Navigate to subscription history
Head over to the "Sales" navigation like and click on the "Subscriptions" link.
Step 2: Find the contact record you wish to cancel the subscription for
Click on the contact record. Down the bottom left of the pop-up window you'll see a button saying "Cancel Subscription" press it once and your be prompted to "Confirm Cancelation" once you complete this you're done. Activerelay will apply the associated subscription cancelation tag on the contact record.