How to remove a redundant Tag

I recently added my Big Boxes back into Roon as the Filter/Focus improvements in 1.8 make them more viable than previous.

Previously I had some Tags set up but later deleted them when I removed the Big Boxes . For example

Now I see on the newly imported albums the Old Tag names show up but if I click on the tag name it tells me the tag no longer exists , I cannot recreate the Tag so I am having to use a less descriptive tag

Previously I could Richt Click the old Tag and delete it

Any ideas or Workarounds ?