1. Create a npm proxy repo
2. Download an npm package metadata through the proxy - make note it references a version, for example 1.0.0
3. The remote site unpublishes version 1.0.0 of the package
4. Go to Browse and select the npm package metadata file - delete it.
The intent of an admin doing this is to bring the locally cached tgz packages in line with what the remote actually has available.
5. Download an npm package metadata through the proxy again - make note it it still references version 1.0.0, even though the remote no longer references that version and that version is no longer cached inside the proxy repository.
If the package metadata is deleted from NXRM, and there are tarballs also cached in the repo that are no longer at the remote, then NXRMs new package metadata should no longer reference the a non-existing version.