Cancelling an app prior to trial period ending

Thought i had measurements tool built into my iphone. XR - 18.3.1 but found none. Found "free 3 day trial" on "Tape Measure" app but it has NOOOO info on how to contact them to cancel before they charge 10 bucks a WEEK!

To measure one wall...! Expensive tape measure. I never used it. I want to cancel the app before the trial date ends and i'm sucked into paying, or be punished for not paying for something I never used and have tried to cancel before the 3-day trial period ends. There is NO WAY given to cancel before the trial ends. Theirs is not a better business practice. How do I cancel the "Tape Measure" "free 3-day trial" SCAM?!