Go to your Prime membership. Select Update, Cancel, and more, and follow the on-screen instructions.
How do I cancel my Amazon Prime subscription?
Membership Cancellation If you signed-up for your Prime membership directly through us, you may cancel your Prime membership any time by visiting Your Account and adjusting your membership settings.
Can you cancel your Amazon Prime membership at any time?
Keep in mind that if you were a paid member (meaning you weren't using a free trial) and used any of the Prime benefits once or not at all before canceling your account, you're eligible to receive a full refund of the annual fee. You get a partial refund if you used Prime four or more times.