You'll need to delete ALL the tags from the fuel ups they are linked to.
For example I saw there was a "hHess" tag. An obvious typo since you have "Hess". I found the single fill up from 2014 with that tag and replaced it with "Hess" and checked your tag list and now the "hHess" is gone.
So any of your 'bogus tags' still visible in the list are attached to at least one entry somewhere.
You don't need to delete the fill up, just edit and remove the tag and resave.
If you can give me a list of the tags you'd like removed, I can help track down where they are.
The "Tag" list does not exist, but is a dynamic reference of all the tag values I have previously entered on any record anywhere. So ... its up to me to find the bad entries and go clean them out. That will "magically" make the tag list clean up.
I had suspected that.
What it took me a while to figure out was that Tags also reside on "Notes" entries. All of the Notes on my Fill-up records were clean. However, I had all kinds of crazy tags on my "notes" records. Luckily, I only had a few notes per vehicle and only a couple vehicles in my "garage". In less than 5 min I found all the bogus tags and cleared them out.