Reading through the replies here there certainly is a range of suggestions!

I think what this points out is that there is no one answer. It depends on your operation. If this unruly heifer is part of a 500 cow herd on a section of land where cowboys and dogs round them up every so often maybe you brush it off as first calf heiferitis.

If you are frequently in close contact as in a smaller rotational grazing system, or a more confined system of some sort then the physical hazard that she might present and the effect on the rest of the herd is more of a concern and selling her might be the best option.

In my case, I frequently have family members including grandkids and also hired HS students in the pasture with me when rotating/moving wires or fixing fences, etc. We are still careful, usually having the Ranger nearby, but I have zero tolerance for any sign of aggression in my herd. 

Yes you want them to defend their newborn calf, and my Hereford mamas do that. This is why I no longer try to tag or band or even touch new born calves. Even the tamest cows should have some sort of defense reflex right after calving. But a month or two later its a lot easier running them all through the corral and chute. But if I keep my distance from them and let them bond right after calving I don't feel any aggression towards me or my family. If we get close mama usually just nudges her calf to come follow her into the woods.

So there probably is no ONE best answer regarding this heifer.