Users with a fingerprint scanner can use their fingerprints instead of a password to log in. Fingerprint login needs to be set up by the user before it can be used.
Fingerprint readers are not always reliable, so you may wish to disable login using the reader for security reasons.
Create the key file
# Specify the dconf path
[org/gnome/login-screen]
# Disable fingerprint reader
enable-fingerprint-authentication=false
To prevent the user from overriding these settings, create the file
# List the keys used to configure login
/org/gnome/login-screen/enable-fingerprint-authentication