How can I permanently delete customer tags?

I mentioned this in an earlier post and my suggestion is that you log your request with Shopify support and ask them to let the developers know you’re also interested in this fix. I think the more we explain how this isn’t just aesthetics, but causing problems for us and send screenshots and explanations of why this is an issue, the more we’ll move the needle.
Best talk to Shopify directly! I think at least two of us have put in the request and vote through support now.