we had the same freeze in phx. anyway= you can lop it off or just take a few branches off its not going to hurt it. they are pretty resilient/
your tree isnt really considered to be a young tree, however it isnt old either. If it were 1-3 years then it would be young. and probly wouldnt have come back. yours has an established root system so its going to be fine.
Personally i wouldnt shape the tree they do well on their own.