I recently encountered an issue where an ESXi host upgrade caused it to lose it’s connection to an iSCSI datastore. I was finally able to get the iSCSI issue resolved, but then I had an issue where I needed to name the newly created connection the same as the previous. The “old” one was still listed as an “inactive” datastore. I couldn’t name it the same as the old one, but there was no option to delete the old datastore reference.
I finally figured out that I had to remove all VMs from inventory that were still dependent on the “old” datastore. As soon as I deleted those VMs from inventory, the “inactive” datastore was automatically removed. Then I could rename my new iSCSI datastore to match the one that the system marked inactive when the original issue happened during the upgrade.