How do I cancel my Amazon Prime membership so I'm not charged again?

Go to Account & Lists > Prime Membership > Manage Membership. Click 'End Membership' or 'Do Not Continue', and Amazon will throw a few 'are you sure' screens with offers at you, keep clicking through to confirm. Key point: if you cancel before your renewal date, you keep Prime benefits until the current period ends, then it just doesn't renew. If you paid annually and cancel early without using benefits recently, you may get a partial refund. Set a reminder for the renewal date so you're not caught out.

Amazon buries the cancel button under a maze of 'stay with us' offers, just keep clicking End/Continue. You're not cancelled until you see the confirmation screen.

You keep the benefits until the paid period runs out, so cancel early and still use it till then. No reason to wait until the last day.

If you barely use Prime, cancelling annual mid-term can get a prorated refund. The 'End Membership' flow tells you if you qualify.