I would start by restarting Spiceworks, then going back to this page to see if anything changes for you. If that fails, I would stop Spiceworks and manually edit the users.yaml file in the data directory of your Spiceworks installation.

Alternatively, you can logout of your Windows account and login as a different user, then start Spiceworks as that user and you should be able to delete any straggling accounts.

It’s not a matter of that user being associated with a scan range, it is the user Spiceworks itself is running as.