This is the new best way to upgrade npm on Windows.
Follow below steps
Go to Window
Type Run PowerShell and open as Administrator
First: Run command ->
Set-ExecutionPolicy Unrestricted -Scope CurrentUser -Force
npm install -g npm-windows-upgrade
Note: Do not run
npm i -g npm. Instead use
npm-windows-upgrade to update npm going forward. Also if you run the NodeJS installer, it will replace the node version.
npm-windows-upgrade -p -v latest.