If you've forgotten your Citibank username or password, visit the Citibank website and click on the "Forgot User ID/Password?" link. For a forgotten username, you'll need to provide your account number, email address, or phone number to receive your User ID. For a forgotten password, enter your User ID and verify your identity through a one-time password (OTP) sent to your registered phone number or email. Follow the instructions to reset your password. If you experience any issues, contact Citibank customer service for further assistance. This process ensures you can quickly regain access to your account.