How to restore/reset npm configuration to default values?

For what it's worth, you can reset to default the value of a config entry with npm config delete <key> (or npm config rm <key>, but the usage of npm config rm is not mentioned in npm help config).

Example:

# set registry value
npm config set registry "https://skimdb.npmjs.com/registry"
# revert change back to default
npm config delete registry

To reset user defaults

Run this in the command line (or git bash on windows):

echo "" > $(npm config get userconfig)
npm config edit

To reset global defaults

echo "" > $(npm config get globalconfig)
npm config --global edit

If you need sudo then run this instead:

sudo sh -c 'echo "" > $(npm config get globalconfig)'