There's no separate cancel button inside PerfectMatch: AI Shopping Quiz — your subscription is managed entirely by Shopify. To cancel, simply uninstall the app:
In your Shopify admin, go to Settings → Apps and sales channels.
Find PerfectMatch: AI Shopping Quiz and click Uninstall.
Uninstalling ends the subscription automatically through Shopify's billing system. Any charges are handled by Shopify and appear on your regular Shopify bill.
Keep in mind that because each billing cycle starts on the Free tier, keeping the app installed costs nothing unless your quiz completions exceed the free limit. If you just want to pause your quiz for a while, you can unpublish it from My Quizzes instead of uninstalling — your quizzes, design, and settings stay intact.
Wondering what happens to your data if you uninstall? See "I uninstalled and reinstalled the app. Will my quizzes be restored?".