To completely uninstall node + npm is to do the following:
go to /usr/local/lib and delete any node and node_modules
go to /usr/local/include and delete any node and node_modules directory
if you installed with brew install node, then run brew uninstall node in your terminal
check your Home directory for any local or lib or include folders, and delete any node or node_modules from there
go to /usr/local/bin and delete any node executable