Hi again Stan,
the first step you should do is to Consolidate the Virtual Machine disk files - and the best would be to do it on all your VMs (if any snapshots are present) that were on the previously migrated datastore, just to be sure you reclaim all the space. Snapshots are delta disks for your point-in-time states of Virtual Machines that you can return to them for example should an application upgrade fail or other short-term VM-disk based change. You can safely do this step on all your current VMs if you don't need the snapshots anymore (consult with the app owner if you aren't their owner).
The second step to do would be moving the "orphaned" VMDKs from the "Original" datastore to a single folder, for example "temp_delete". If the move is successful you will know that the file is not locked and therefore not used. After all leftover files were moved without problem, you can delete the folder safely.
By the SSH session I mean the direct connection to the ESXi host itself (srvbl01,... etc.) - ESXi has a busybox console that can be operated in unix-like fashion, and there you can see what files are locked with the lsof | grep virtualmachinename.vmdk, but I guess you won't be needing them ![]()
Good luck!