Is there a block on using /D or /DELETE on inventory imports ..

I am working on deleting quite a few "dead" inventory items .. never used, only put in to avoid the use of Nonstock inventory... and have to reconfigure a very large, intimidating database for one of our suppliers ..

I wanted to delete the unused data, and make the corrections needed to the balance of the database, and then reinstall the added data again. 

I put together my database, saved it in CSV format, and I received a message of "INVALID IMPORT FILE FORMAT The selected file is not a valid part information file or the file is empty"

I verify the file has information in it .. and did sample imports into my dummy company (copy of my real company .. love this feature) changing some of the file to /A or /ADD ..The /A or /ADD worked fine .. but didn't delete any of my "sample parts" ...

Is there a "trick" to using the /D or /DELETE in "Inventory transfer" file .. ???