With the cli I don't know if it's a remove command but you can remove it from package.json and stop using it in your code. If you reinstall the packages you will not have it any more
It's an open issue #900 on GitHub, unfortunately at this point of time it looks that in Angular CLI there's nothing like ng remove/rm/..., only using npm uninstall DEPENDENCY is the current workaround.
Sometimes a dependency added with ng add will add more than one package, typing npm uninstall lib1 lib2 could be error prone and slow, so just remove the not needed libraries from package.json and run npm i