Cannot change npm global location - node.js

Question

looks like i messed up something with npm, and i don't know what should i do.
environments:
- Amazon Linux (EC2)
this is the story:
I installed nodejs with yum: "yum install nodejs npm --enablerepo=epel" on my server few months ago.
and then, i knew that there were node version manager(nvm), so i removed my node.js and install the nvm, and then installed latest node.js
but looks like there were something messed up with nvm settings(recently realized) so i removed nodejs with nvm, and then removed nvm.
then i re-installed node.js with same above with yum command. it looks fine, nodejs worked well, but there was big trouble with npm. i checked the location of global modules with command "npm root -g" as normal user(ec2-user), it prints
npm ERR! Error: EACCES, mkdir '/root/.nvm/versions/node/v5.5.0'
npm ERR! { [Error: EACCES, mkdir '/root/.nvm/versions/node/v5.5.0']
npm ERR! errno: 3,
npm ERR! code: 'EACCES',
npm ERR! path: '/root/.nvm/versions/node/v5.5.0' }
npm ERR!
npm ERR! Please try running this command again as root/Administrator.
npm ERR! System Linux 4.1.13-19.31.amzn1.x86_64
npm ERR! command "node" "/usr/bin/npm" "prefix"
npm ERR! cwd /home/ec2-user/modernator
npm ERR! node -v v0.10.42
npm ERR! npm -v 1.3.6
npm ERR! path /root/.nvm/versions/node/v5.5.0
npm ERR! code EACCES
npm ERR! errno 3
npm ERR! stack Error: EACCES, mkdir '/root/.nvm/versions/node/v5.5.0'
npm ERR!
npm ERR! Additional logging details can be found in:
npm ERR! /home/ec2-user/modernator/npm-debug.log
npm ERR! not ok code 0
so i logged in to admin, and typed same command "npm root -g", it prints:
/usr/lib/node_modules
looks like something is messed up when i removed nvm. everytime i tried to change npm prefix or just try to get any config from npm as normal user, always fail with same error messages!
but if i try with sudo("sudo npm root -g"), it says "/usr/lib/node_modules".
i spend to solve this problem for days but i still working on. and still i don't know even what should i do. every posts found from google not worked. i removed and installed nodejs plenty of times, but not worked. please god, if someone know how to solve this, please give me a advice.

Answer 1

You don't have access by default to root resources.
When you perform this:
npm root -g
It tries it for root user, i bet you need to change user:
npm $USER -g