Any luck after host or vCenter restart?
You can double check with network person if they are able to see the MAC on their network devices connected with these ESXi hosts.
Also, check with backup guys if they have configured this datastore in their system and get it removed and then try again.
Same goes for any 3rd party application configured to work with vCenter in your environment, if any.
I talked to the network guy and he found me an IP that goes with the MAC address.
I will try and delete the file later today from that server.
That solved my problem. I was able to delete the files on the LUN from that server and It's now been successfully removed.