Welcome to the forum. You can cancel your passes yourself by going to your My Account > My Passes page on the website.
You should see a list of any active passes you have on your account, with a cancel button next to them. Just click cancel and follow the steps all the way to the end.You should receive an email confirmation but you might want to take a screenshot of the cancelled pass as well.
If you have more than one type of pass you need to cancel each separately.