Trim it back to just above the new growth.....or just leave it. Either way, you've dodged a bullet! You'll have to be careful not to disturb the new growth though.

Personally, I'd leave it. Maybe trim it later, but not now.

I would remove as much of the dead area as you can before those branches grow past the dead line. Once that happens you have a much harder time manipulating any cutting tools without taking out one of your new green branches.

Just wanted to post an update! I removed the dead area and left it in ground. It did really well shooting up and leafing out this summer. It even hung in there through 2 hurricanes although it did lose a few leaves. I couldn’t believe the inflow last week when I checked on it! I wonder if I’ll see flowers?!

That plant of yours is extremely resilient. The plumeria is one tough plant in many ways..."it takes a lickin' and keeps on tickin'..."