So I physically pulled some (Virtual) disks from a TrueNAS Core system. Disks are gone, all data on them was gone. They were a test pool before I powered up some external drive trays to get things going at high power mode. Now I've got this remnant in the UI which shows the old pool, and I can't find anything to remove it. I assume I need to edit a file or remove a configuration or something somewhere, but I'm a bit at a loss as to what to do to get rid of this annoying artefact.

Also note, I migrated all my data off of this pool before I removed it entirely. I made sure I didn't need the data anymore, and so I'm not looking for data recovery or backup help. Also, the system wouldn't let me zpool export the drives even after a reboot, and because of a small change in the latest TrueNAS Core, I couldn't make any pool changes in the UI because the disks all had the same (read: no) serial number . Worked before the update, not after. Anyway, I need to file a bug report about that, but it's unrelated to solving my problem now.