Disclaimer: This information is provided for legitimate security auditing and administration of hardware you own. Unauthorized access to printers you do not own is illegal under the Computer Fraud and Abuse Act (CFAA) and similar international laws.
The ( root / public ) is a temporary key, not a permanent solution. It exists to get you into the configuration screen so you can set your own credentials. citizen printer default password
If you bought a used printer and the previous owner changed the password, you cannot guess it. You must reset the hardware to factory settings. citizen printer default password
Here are some common default passwords for Citizen printers: citizen printer default password