Hide Series from the Legend when NOT null

Searched using several different phrases but wasn't able to locate anything from previous threads on this except "Hide Series from the Legend when Null" which didn't help in this situation, so figured it would be quicker to post since it seems like a pretty easy question to get an answer for, or be advised that at this time it's not possible though it'd be nice to see if this could be considered for a feature request if it can't be done.

We're using color rules to differentiate call center agent tardiness for adherence purposes, and while the legend shows agents =< 10 minutes late in GREEN & those > than 10 minutes late in RED as we want, it still shows the series label within the legend; this isn't necessary since we already have the labels we need, and also tends to clutter things up a bit. Is there a way to hide this? Even leaving the label blank doesn't help since it just pulls the field name (see screenshot).

Thanks in advance for any assistance on this.