Since this the top google result, this is what worked for me:
Update, if you have npm v5, use npx:
npx rimraf ./**/node_modules
Otherwise install RimRaf:
npm install rimraf -g
And in the project folder delete the node_modules folder with:
rimraf node_modules
If you want to recursively delete:
rimraf .\**\node_modules
[ http://www.nikola-breznjak.com/blog/nodejs/how-to-delete-node_modules-folder-on-windows-machine/ ]