如何卸载Node，NPM，yarn

I'm on a Mac (High Sierra 10.13.3). I switched from NPM to yarn a few weeks back. Recently, yarn has been giving me issues when attempting to global install various tools and libraries (webpack, etc) saying that "an incompatible module "node" was found. Expected version 6.11.0". I've tried using NVM, but I only get back a response that says "This is not the package you are looking for". I'm on a Mac (High Sierra 10.13.3). I switched