I'm looking for a way to clear a specific tag from all Leads.

I have a function when a tag is added to a lead they are added to a campaign and their status is set to "invited".  I need to find a method to remove the tag.  If I try to delete the tag to clear it from the Leads I have to add a placeholder since it's used in that workflow.  I'd like to see if there's another method, perhaps a standalone deluge function.  I've seen some examples but they seem to rely on knowing the IDs of the leads.  

For example I want to take a specific tag "Tag123" and remove it from all leads.  What would the deluge script be for that?