Following these steps will erase all accounts from your Yubikey.
On your computer, download and install the Yubikey Personalization Tool from the Yubico website.
Once the program is installed, insert your Yubikey into a USB port.
Wait until the light on the Yubikey is a solid green. (If your computer prompts you to set up a new keyboard, close the window and continue to step 4.
Open the Yubikey Personalization Tool.
Select Yubico OTP Mode.
Click on the Quick button.
Select Configuration Slot 1.
Uncheck Hide Values.
Click the Write Configuration button.
If you are warned about overwriting the values in slot 1, click Yes.
If you are asked to save a log file, you can save it or cancel.
Leaving the Yubikey Personalization Tool open, continue to Enrolling the Yubikey.