esxcli I used in the past for a similar Problem.
Here its looks like a little bit more chaos.
The Datastore are not attached to any Host. In the Datacenter are no hosts attached. The hosts that I removed, don't attached to this datastore. The Networks are from an old Project. I cannot remove the Networks, the option is not active. I think, the other guys just shutdown the Hosts and don't cleanup the environment. No VMs are attached to the datastore/network (the lists are empty).
I check the folders with the apiexplorer for the Datastore. I think I try to remove the artifacts from the DB, but IMHO it is the best, I save the Configs, Keys, DRS Settings and Setup a new VCSA. The VCSA was in the past a Windows System (since v5) and we have so many changes since then.