All questions tagged with csv seem to be about CSV.
I wasn’t sure if I should simply delete the wiki content (it’s rather detailed), or if there is a process to migrate it to a new tag.
You can go ahead and write a new tag wiki for it. The old tag wiki will be preserved in the revision history in case we need to reference it again if a cvs tag pops up.
Since we don't have any questions that I can see that should be tagged with a cvs tag, there's no use in creating a tag for it now. It would just be culled when the tag-cleaner runs.