We're sorry to hear that you want to cancel your monthly billing. If there's anything we can do to convince you to stay at your current level, please reach out to us and let us know.
In order to cancel your subscription, log into the BookSprout website. Once there, go to your author area and click on PLAN & BILLING in the top menu.
On the PLAN & BILLING page, change your plan to the free plan. This will stop the monthly billing and change your account to the benefits which come with with the free plan.