Correct and I have used the cloud client to remove vm's in the past but I have 600+ vm's that need removed. I want to provide a file with all the names and have a script use cloud client to remove them all so I am not inputting them in one at a time.
I'm not sure how to automate this using cloud client but maybe you could use the stored procedure from the KB article?
go to managed machines, type missing in state so ,it shows missing only (create filter);.
Then select all (top left), hover over one of them and select unregister. it will give you a list to approve. only does 30-ish at a time (whatever fits to window)
if thats not an option it needs scripting with cloud client:
on a note, you can find this logged here: C:\Program Files (x86)\VMware\vCAC\Server\Logs on IaaS
there's a file MissingMachines.txt
also bulkimport is not the right tool I think as for import VRA needs to see the VM. if it cannot 'see' it, its missing. I think first find out if the VMs were deleted, or if its because VRA cant access the vCenter anymore (or cluster)