Write to hello@nanuli.app and a person will answer. Include the device you are using and what happened; if the app misbehaved during a recording, say which story and which scene.
In the app, on the device you made them on. Your recordings and your child's name never leave the device, so nothing can be recovered by us. Keep your device backup on if the recordings matter to you.
Settings, then "Delete all recordings". They are gone immediately and for good. Deleting the app removes them too.
Settings, then "Manage subscription" — it opens Apple's subscription page. You can also go to Settings on the device, tap your name, then Subscriptions. Cancelling stops the next renewal; the period you paid for runs to the end.
Stories you have already recorded keep playing. Stories you have not started lock until you subscribe again.
The recording never leaves the device, so nobody else can hear it — not us, not Apple. If you would rather record alone, choose "I’ll read every part myself" when a new story asks who reads, and the story stays in one voice.