If you have lost your two-factor authentication device, you can still login if you generated backup codes and saved them during the two-factor setup process. If you have access to your backup codes, login with your username and password to Account Management at https://oauth.iracing.com/accountmanagement, then click on Enter a backup code on the TOTP screen.
Enter one of your backup codes to complete logging in. Then follow the instructions in How do I disable Two-Factor Authentication?
If you do not have access to any of your backup codes, please contact Customer Service at [email protected] and they will help restore access to your account after verifying your identity.