Uninstall a package programmatically
npm.commands.uninstall(packages, callback)
This acts much the same ways as uninstalling on the command-line.
The \'packages\' parameter is an array of strings. Each element in the array is the name of a package to be uninstalled.
Finally, \'callback\' is a function that will be called when all packages have been uninstalled or when an error has been encountered.