I've followed this method, originally designed for packages with blank names that can't be accessed through the interface. But I've also used it since then for packages that can't be accessed through the interface, even if they do have names:
http://www.symantec.com/docs/TECH143021
It should also work even without a delete option. But be sure to try accessing it through Resource Manager first, since that should offer you the Item References report, which is important to use in case other items are depending on the resource. Item References allows you to make changes before you delete the referenced resource.
Does this answer your question?