Personally, before I deleted those, two of my user accounts were using the latest version of node/npm installed correctly via nvm, while a third account of mine remained stubborn by still using a far older installation of both node and npm apparently located inside my /usr/local/bin/ directory. As soon as I deleted both of them with the two above commands, that problematic user account implicitly began running the correct installation, having all three accounts mutually the intended versions.