Poison Ivy - The Persisting UKtrees Tag

The tag UKtrees has mysteriously appeared on all posts about Ivy. I thought I had managed to remove
them all but one post is being particularly stubborn -

I have tried at least 3 times and Derek has tried too, but the tag persists.

Another mystery. I thought I would apply filter again to try to get rid of it, but no results appear for Hedera helix by wortmaggot
Oh well.

Stop Press : The problem has been solved by Mags.
I deleted UKtrees but at the same time replaced it with a different tag.
Thank you Mags

Well raised, thanks. That particular tag issue has been with us since the beginning and it has been noted before in a Forum Item.
Yes, it has a simple solution: add an innocent tag like urban or rural (FROM the tag list) then remove the stuck tag, This applies to ONLY a solitary tag you want to delete.
Please (everyone) consider using less tagging and only those which are Collection tags, like UKleaves and nothing that is implicit in the Observation, like Nottingham, green or bigmoth. Before INVENTING a tag please look first in the tag list and perhaps ‘ask around’

Don’t give up, Derek!