To cancel Grok, make sure you use the exact billing channel you originally...

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

To cancel Grok, make sure you use the exact billing channel you originally signed up with—whether that’s grok.com/Stripe, Apple Subscriptions, Google Play, X Premium on x.com, or console.x.ai for Business or API billing