For the most part you are correct.  The main thing is to have all LUNs and RGs destroyed, nothing bound on those trays to be removed.  Secondly, I would swap steps 3 and 4.  You should first disconnect the HSSDC2 cables (do one side at a time and wait 30 seconds before moving onto the other, array must be aware of removals), then power off the DAE.  Yes, finally restarting the management server on both SPs is the final step to remove the ghost DAE in the navisphere tree.
I would like to remove 2 DAE's from our CX3-10. Is there a specific step-by-step instruction that I need to follow? I noticed that neither NST or USM have instructions on how to remove a device.  I was thinking on these steps: 1.unbind LUNs 2.delete RG 3.disconnect power on DAE 4.unplug the HSSDC2 cables 5.restart the management service??? 
DAE Removal