Manage your YubiKey via the YubiKey manager application (Reset Security PIN)
The YubiKey manager installation file is found here, choose the correct download file for your Operating System.
If you have forgotten your Hardware Token Security PIN, the Yubikey Manager desktop software lets you to Reset your PIN (restore it back to default). The Hardware Token can then be set up again via your Microsoft account
Open the YubiKey Manager application and insert your YubiKey
Click on the Applications tab and choose Fido2
Now you have 2 options, Change the Pin or Reset (Restore defaults) this will wipe all FIDO credentials.
To restore to Default, click Restore FIDO and click Yes to Confirm
You will be instructed to remove and insert your YubiKey Hardware Token
And finaly to Touch the Sensor on your YubiKey to complete the process
Quick Access
Useful External Links
Don't forget to set up more than one MFA authentication method for your Single Sign-On! If your phone is your only method and is lost, replaced or stolen, you could temporarily lose access to your account. Guides here: https://help.it.ox.ac.uk/mfa-setup-and-management
Key thing is to make sure you have a backup MFA method. If you are old enough to still have a landline then registering this is a good idea. https://twitter.com/ITBrasenose/status/1471431860836315137
Need guidance on how to set up multi-factor authentication on a new phone, or if your phone is lost/stolen? @ox_it have you covered with this handy guide: https://help.it.ox.ac.uk/mfa-setting-up-multi-factor-authentication-on-a-new-phone