I never had an audio message for a print that needed to be reset. To make sure it is actually coming from your security settings, download Good Lock's Nice Catch and turn on sound history. Next time you get that audio, check the app to see where it's actually coming from. It could be some random malware that's trying to get your fingerprint.
Do your registered prints actually work? Do you get this message when you try to use your fingerprint? It sounds as if there is some accessibility feature that has been activated to give you audio notifications. But, you would only get that message if you were trying to register a new print and the print you are trying to register already exists.
If you don't want to do a full factory reset, there are a couple of things to try first. One being the aforementioned Good Lock module to identify where the notification is actually coming from. You can also: clear the app cache and data from the security policy app and the biometrics app and data cache from the biometrics. You will have to set up the policies and biometrics again. You can find these settings by enabling system apps in the app search and searching for security policy and also biometrics. You can try clearing the phone's cache partition. If none of these measures stop the nagging, a factory reset may be your only recourse. Backup your personal data to a flash drive or Samsung's temporary cloud storage using Smart Switch. All the non-personal data, apps and settings will be restored when you restore the Samsung backup. Biometrics and passwords, patterns and pins are automatically erased in a reset and would have to be re-established.
