I want to cancel a 7 day free trial app that my daughter downloaded it’s called 30 day fitness challenges. I don’t want it and I can’t cancel

People on this forum are other users like yourself and cannot do what you request. Apple does not respond here.

View, change, or cancel your subscriptions - https://support.apple.com/HT202039 - "Learn how to view your subscriptions that renew automatically, change your subscription period, and turn off Automatic Renewal." "If you don’t cancel more than 24 hours before your renewal date, your subscription might renew."

iTunes [Store] Support Contact - https://www.apple.com/emea/support/itunes/contact.html

Hi,

Just follow: View, change, or cancel your subscriptions - Apple Support after that, you should be fine.

If you can't see a cancel subscription option:

This means that the subscription has already been cancelled. You will then be prompted a date on up until when will it be active, after that, it will automatically expire.

But remember cancel the subscription before the renewal date as it will still charge you if you don't.

Hope this helps!