I'm not a Windows user, so if you are, try to check Rene Knop comment.
For Unix/OSX users, I've removed the root .npmrc file ~/.npmrc
.
Before you're going to try it, please,
check if there is nothing necessary over there
you can use this command to bring all content into your terminal: cat ~/.npmrc
.
If you have got something like:
cat: /Users/$USER/.npmrc: No such file or directory
to save a copy:
cp ~/.npmrc ~/.npmrc_copy
Now, try to remove it (Works for bash users: Unix / Ubuntu / OSX ...):
rm -f ~/.npmrc
This worked for me.
Hope this will be helpful for others.