Please visit the following link to Disney+'s site to find instructions on cancelling your subscription: https://help.disneyplus.com/article/disneyplus-cancel
Here is an excerpt from their site with instructions on cancelling:
If you’re billed directly by Disney+ you can cancel your subscription by following the steps below:
Log in to your Disney+ account through a computer or mobile browser
Select your Profile
Select Account
Select your Disney+ subscription under Subscription
Select Cancel Subscription