When you sign into your membership, please click on the Premium user ID in the top right. If you do not see "Premium" in the user ID then you are signed into your Basic (free) account and will not see the option to turn auto renew "off". This means your Premium membership is under a different email address.
Otherwise, if you are signed into your Premium membership and have selected your Premium user ID, you can then select "Account Settings from the dropdown or click this link: https://www.education.com/my/account/. This will take you to your membership account page and under Plan Details you can select "Cancel Subscription" to turn off auto-renew.
If you prefer, you may also contact us when you are ready to cancel and we can take care of it for you.