You can see your current subscription and cancel it if you want to from your membership options page when you are logged in.
At the bottom of the page you will see a grey button like this:
You will be asked to confirm and then your subscription will be set to auto-cancel at the end of the subscription period. I.e. if you are a monthly subscriber it will be at the end of that month or, if annual, at the end of that annual period. Your membership and access to the site will also continue until the end of the period.
If you want an immediate cancellation and refund then please get in touch with us and we'll press the appropriate buttons from our end.