If you see the old video feed still showing up? You didn't hold the button long enough. Try again. Disclaimer: Only reset cameras you own legally. Do not attempt to reset rental equipment or cameras installed on property you do not control.
The good news? You don’t need to throw the camera away. You just need to reset it. However, There is a distinct difference between a Hard Reset (password removal) and a Factory Default (wipe all settings).
Maybe you bought a used camera from an auction. Maybe the previous installer left without handing over the password. Or perhaps you simply forgot the "Admin" credentials you set up three years ago.