That's odd. When I go to the passwords/biometrics screen it only asks for my current password to enter the secure area. I have fingerprints set, but it is not my primary unlock method - my password is, perhaps that's why. Run a diagnostic on the fingerprint sensor to make sure it's actually working. If you haven't already, you might want to try wiping the phone's cache partition and trying to enter biometrics again. If that does not work, I'm afraid your only recourse would be to reset. Diagnostics can be found in the device care settings of your phone.
In any case, if you cannot get into the secure area to reset the biometrics and the fingerprint sensor is working, I suggest you make a complete Smart Switch backup of your phone, either to the temporary cloud storage or a flash drive, as the only way to clear out all the security lock data is to reset the phone. This information is never saved in a backup, so your phone will be unsecured after restoring you backup until you set the security method. You can restore your backup either before or after re-securing your phone.
