You can cancel Prime Video Channel subscriptions at any time.
Your subscription end date displays on the confirmation screen. You can reverse your cancellation until that date. After which, you will no longer be charged, or have access to content from that channel. Canceling a subscription does not generate a refund for any previous subscription charges.
You need an Amazon Prime membership to access Prime Video Channels. If you cancel your Amazon Prime membership, your Prime Video Channel subscriptions also cancel.