Imagine an autoregistration rule in highly dynamic environment. One of thh tags is location:something ( dc1, dc2, dc3, dcN), it gets assigned to a host. In case the host moves from location:dc1 to location:dc2 you can add the tag automatically/easily ( location:dc2 ) but if you'd like to remove the tag location:(dc2|dc5|dc8|dcN) you need to know exactly the combination key:value. It's not very good for automation. I think there should be and option to remove tag(s) from host identified just by the key - regardless of their value.