@Joshua8600,
Thanks for reporting this bug and explaining how you were able to remove the lingering Moderator flair.
I took the liberty of editing your solution to simplify it slightly - you can navigate to the user’s account preferences page as Admin and select none for the user flair without having to impersonate the user, so it’s a little less invasive as a solution that way. 
I’ve also been able to repro the issue and your solution and we’ll look into getting it resolved.