Want to cancel an app that was a free three day trial I didn’t realize til I downloaded it that you had to pay if I delete it will that cancel it cannot afford to be billed thanks

You must cancel a trial subscription 24 hours before the last day of the trial to avoid being charged.

Deleting an app does not cancel a subscription.

Managing auto-renewing subscriptions -

If you want to cancel a subscription from Apple - Apple Support

M1 Mac mini, macOS 14.3;  Watch, series 7 GPS/cellular, watchOS 10.3; iPhone 12 Pro, iOS 17.3; TV 4th Gen, tvOS 17.3; HomePods, audioOS 17.3 and Airport Express w/ Airplay 2

If Apple has charged you, you must pay. You can then try to ask for a refund.

First confirm you have canceled any subscription automatic renewal (if you simply delete an app this does not cancel subscriptions):

Review the information in this support article by clicking on the link to learn how to cancel a subscription from Apple. ➔ If you want to cancel a subscription from Apple - Apple Support

• "If you signed up for a free or discounted trial subscription and you don't want to renew it, cancel it at least 24 hours before the trial ends."

• An existing subscription will normally continue until the end of its term and may then renew automatically. Stopping automatic renewal is effectively canceling it. "If you don’t see Cancel Subscription, then the subscription is already canceled and won't renew." The "Expires" date means the current subscription will just run until then.

• Read the article to see what to do about subscriptions that do not appear in your list. If you still can't find a subscription, contact Apple Support using the link at the end of the support article.

• Canceling a subscription does not automatically start a refund.

Finally, follow the directions in this support article about how to request a refund for apps or content that you bought from Apple ➔ Request a refund for apps or content that you bought from Apple - Apple Support