For Premium and Legacy Members, click the Cancel Premium button at the bottom of the My Membership page within My Account, which will turn off automatic renewal, allowing your Membership to expire at the end of the current term. 

If, after canceling, you want to enroll in automatic renewal again, you may do so only if you are a Premium Member when manually renewing your Membership for one year toward the end of the term. During that transaction you may select to enroll in auto renewal, which will be applied to the following renewal, one year later.