Hello, this is Emily.
Go to https://account.live.com > sign into your account. Click on Service & subscription, and you can find it there and cancel it.
If you need any refund and the option is not available, because this is a public forum, for your privacy and security, refund matter cannot be discussed here, nor does anyone helping here have access to such data. You will need to contact support to get it handled. On your computer, launch the Get Help app from the start menu, then type in Refund as the keyword. On the next page, you can click on "Contact support" button. Then fill out a few more details and you will be directed to the page where you will have the option to chat with a live support agent.