Email hello@tirus.app and I'll reply myself, usually within a day.
In the app
Settings ▸ Support ▸ Send feedback or Report a bug. It adds your app version, iOS version and iPhone model, never your memos.
On TestFlight
Take a screenshot in Tirus and tap Share Beta Feedback.
Delete everything
Settings ▸ Delete all data. Your recordings and notes live only on your iPhone, so deleting the app removes them too.