First, I am not sure if you mean "corral". That usually would be something like 60 by 100 -and not a good place to work a horse like that.You need a small pen.

I bet you the person you bought the horse from had a reason to leave the halter on all the time - as you are finding out now. Most likely something bad has happened in the past. And also most likely you never will know.

Here is what I would do. You need a pen of about 12 by 12. Put her in there and stay in there with her. Don't try to put the lead rope on. Get her used to beeing close to you This might take a while.

Here is a trick I use with babies or a horse like that. Every horse has itches. As soon as I see a horse nib at some spot, I will scratch that spot - real hard. It usually does not take to long and the horse will think you are the greatest thing on earth.

The next step would be to scratch her with the rope in your hand or hanging over your arm. This way the horse will learn to like the rope. You can at some point wrap the rope around the neck or the legs and "scratch" the horse with the rope.

Try if that will get you anywhere. And by the way a horse turned out with a halter on is a bad idea. The horse could get hung up on something. Worst case the horse might kill itself - best case you can forget the halter forever.