SnackyStacky put me on the right path, although I wasn't able to delete the app from within TestFlight. Instead, this worked:
Swipe right until you get to the search box
Type the name of your app until the small preview icon appears
Long press the small preview icon
Tap Delete App (at the bottom of the dropdown list), confirm.
As of May 2022, on my wife's hand-me-down iPhone 7 Plus. ;) running iOS 15.4.1
tom_eberhard
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