How do I cancel my subscription?

Purchased one year subscription by accident and meant to purchase 1 month. How do I cancel? Support emailed me:

"Link to cancel it can be found from your "Thanks a lot for your purchase" email that you received from info@supermetrics.com."

There is no link in that email other than to the account management page which has no clear way to cancel subscription.

Please help as supposedly I only have 24 hrs to get a refund.