Hello, this is NOT an authoritative answer, but some insight that casts some doubt on your question asking if IP Address records can be deleted if Nic and Nic.Configuration Item are blank. I think the answer is no, unless you confirm a few things.
I looked at a list of IP Address records where those two fields are blank, and then I searched cmdb_ci (excluding the IP Address class) for records with the first IP on my list, and found a Network Adapter with that address that was one of the network adapters on an active Firewall. So, at the moment, my hypothesis is that we might be able to delete IP Addresses if: 1) Nic and Nic.Configuration Item are empty, 2) don't exist as the IP Address for any CI.
Another caveat is that deleting these IP Addresses when they are still associated with something like this example might cause ServiceNow to create another IP Address CI record, which means there will be new associations and relationships as well as the now-orphaned existing ones.
I came across your post since this is something we're also actively trying to understand, and if you haven't solved your issue, hopefully this helps you avoid any possible problems. As we learn more, I will share.
