sudo npm uninstall npm -g  
sudo rm -rf /usr/local/lib/node 
sudo rm -rf /usr/local/lib/node_modules
sudo rm -rf /var/db/receipts/org.nodejs.* 
sudo rm -rf /usr/local/include/node /Users/$USER/.npm*
sudo rm /usr/local/bin/node   
sudo rm /usr/local/share/man/man1/node.1  
sudo rm /usr/local/share/man/man1/npm-*
sudo rm /usr/local/share/man/man1/npm.1 
sudo rm /usr/local/share/man/man1/npx.1 
sudo rm /usr/local/share/man/man5/npm* 
sudo rm /usr/local/share/man/man5/package.json.5 
sudo rm /usr/local/share/man/man7/npm*
sudo rm /usr/local/lib/dtrace/node.d 

原文:
Mac电脑使用： 完全彻底卸载node的步骤