To cancel a free Amazon Prime trial, click the Manage Prime Membership link on the account page, then click do not continue. If the trial is not ended, it is automatically upgraded to a paid membership when the trial period ends.
On the same page, the end date of the trial is listed on the left side. Even after choosing the do not continue option, the benefits of having a prime membership remains available until this date.
In addition to free trials being set to automatically begin a paid membership when the trial ends, current paid members also have their account renewed each year by default. If someone wishes to end their paid Prime membership, they can do so on the same page by selecting the end membership option. Those who have a paid membership may be able to receive a full refund, if they have not placed a Prime eligible order. However, once an order has been placed by the Prime member or someone in their home who is sharing the account, a refund will no longer be available. Up to four members of the same household can share a Prime account by going to the Manage Prime Membership page and clicking the invite a household member option.