Avamar: Deleting a DataDomain?

I've run into an issue when trying to delete a DD660 from my Avamar 6.1.1-87 environment...

Using the backup management I have long since expired all backups residing on the target. All policies we modified to use a different DD target.

I still receive "Cannot delete a system with backups or checkpoints" whenever trying to delete the target.

Searching the knowledgebase indicates an undocumented CLI command, with no hint as to what that command is?

Any guidance appreciated!