As commonly known, any npm module can be installed by running a simple command:
npm install <module_name>
npm uninstall <module_name>
The command is simply
npm uninstall <name>
The nodejs documents https://npmjs.org/doc/ have all the commands that you need to know with npm :)
A local install will be in the
node_modules/ directory of your application. This won't affect the application if a module remains there with no references to it.
If you're removing a global package however, any applications referencing it will crash.