The OTP applet on the YubiKey cannot technically be reset to the factory defaults. To emulate a factory reset, you can delete the credentials from both slots, program a Yubico OTP credential to slot 1, and upload the credential to YubiCloud. Warning: The steps in this guide will permanently delete the credentials stored in the two programmable slots in the YubiKey.
Step 1 - Deleting the Credentials
- Download and install the YubiKey Personalization Tool.
- Open the Personalization Tool.
- Insert your YubiKey to the computer.
- Verify in the right column that the YubiKey is identified.
- Click on the Tools tab at the top.
- Click the Delete Configuration button.
- Select Configuration Slot 1 and click the Delete button.
- Select Configuration Slot 2 and click the Delete button.
Note: If you receive the error "YubiKey could not be configured. Perhaps protected with configuration protection access code?" this indicates the slot is protected. You will need to check the Use Access Code box and enter the access code used when programming. If you do not know this code, there is no way to delete the configuration from the slot.
Step 2 - Programming a New Yubico OTP Credential
These steps are best covered in the Configuring Your YubiKey for YubiCloud guide.