To cancel your ChatGPT subscription, use the same billing channel you signed up...

https://tango-wiki.win/index.php/Does_Deleting_My_OpenAI_Account_Cancel_ChatGPT_Billing%3F

To cancel your ChatGPT subscription, use the same billing channel you signed up with—whether it’s on the web, Stripe, Apple, Google Play, Business, or API. This ensures your cancellation processes smoothly without extra steps