To cancel your Amazon Music subscriptions, you will have to follow these instructions and then get your answer on
How to Cancel Amazon Prime Music.
Open the Amazon site and enter your account.
Open the menu and go to Amazon Music Settings.
Locate the line to which your Amazon Music subscription (e.g., Amazon Music Unlimited) corresponds.
You will find the information on the Subscription Renewal.
Now click or tap on the option marked as Cancel in the subscription renewal information.
There are on-screen prompts to follow to make sure it is cancelled.
Important Notes:
Amazon added that when you subscribe to Amazon Music Unlimited via Apple and iTunes, you should cancel your subscription via Apple.
It suggests that you will still be able to use Amazon Music up to the expiry of your current billing period.
Amazon.com allows some subscription plans to freeze their subscriptions and gives them a chance to review their subscriptions later instead of canceling them.
You might not be in a position to cancel your subscription when you have an annual plan.