To find instructions on how to cancel your Peacock subscription, please visit the following link on their site: https://www.peacocktv.com/help/article/cancellation
Below, we will provide an excerpt of that page showing instructions:
To cancel your plan, follow the steps below:
Log in to your account.
Go to Plans & Payments.
Select Cancel Plan.
Once confirmed, you will see a confirmation message on screen and receive a confirmation email, which may take a few hours. Your plan will not renew at the end of your current billing cycle.