Resetting Your YubiKey 4 or YubiKey NEO to Factory Defaults

The YubiKey 4 and YubiKey NEO have five separate applets, all of which have different processes for being reset. Each applet is listed below, along with the link to the article that covers the steps for resetting it. 

AppletReset Instructions
OTPResetting the OTP Applet on the YubiKey
FIDO U2FThis applet is not configurable and cannot be reset.
PIV (Smart Card)Resetting the Smart Card (PIV) Applet on Your YubiKey
OATHResetting the OATH Applet on the YubiKey
OpenPGPResetting the OpenPGP Applet on Your YubiKey