Cancel subscription – Screen Mirroring for Fire TV® Review

Today I downloaded the app because of the free 3 day trial however, message popped up and said I had to subscribe in order for it to work for iOS. I did so and for whatever reason it’s not discovering tv. As a result I want to cancel my subscription before I am charged 14.99. There is no option within the app to cancel subscription. How to I cancel before charges occur?
Review by ZETTE2021 on Screen Mirroring for Fire TV®.