yubico-piv-tool -a reset
Erases all keys and certificates stored on the device and sets it to the default PIN, PUK and management key. This will only affect the PIV portion of the YubiKey, so any non-PIV configuration will remain intact. Resetting the device will not erase the attestation key and certificate (slot f9) either, but they can be overwritten.
To reset the device, the PIN and the PUK need to be blocked, which happens when entering the wrong PIN and PUK more than the number of their retries.