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She would have to be 18 years of age for emancipation from ones parent in all US States this would include moving out. She must be 18 to legally move from her parents property unless she gets emancipated by a court of law which isn't easy to do. She would need to petition the courts for emancipation and if her parents do not consent it is unlikely this would be approved.
You are still legally responsible for her until she is 18. If she leaves and you fail to report her as a run away you can be held liable for any actions and for any incidents she has. Should she become hurt while away you could be charged with neglect as well.
Here is a link with further information on the subject:
Emancipation of Minors - All US States