By using the delete method on an AddOn or UpgradeAddOn object, you can remove those objects from a domain's Global Configuration Database (GCD).
You can delete only AddOn objects that have not been installed in an object store; any AddOn objects that have been installed in an object store cannot be deleted.
You can delete UpgradeAddOn objects that have been successfully installed in an object store. However, deletion of an UpgradeAddOn is prevented if the UpgradeAddOn object references any installed AddOn objects in its FromVersions property. This particular state indicates that the UpgradeAddOn object has not completed its use of the referenced AddOn object. After the UpgradeAddOn object has been successfully installed and its FromVersions property no longer references installed add-ons, it can then be deleted.