Another possibility: the Tag Wrangler can now rename tags, and does so intelligently for both body tags and front-matter ones. It uses Obsidian’s own indexing to know what is a tag and what isn’t, so it won’t change things in e.g. code blocks or comments. Do review the docs and make a backup before you start renaming, but it’s now an option.
(I’ve considered adding tag deletion as well, but given that it’s a destructive operation with no undo, well… seems better to do it with an interactive search and replace, or to just merge the tag into another tag – i.e. rename it to the same as an existing tag. This will “delete” the old name from the tag pane, at any rate.)