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Thank you for your inquiry.
Unfortunately, as contract between a minor (ie. under 18) and an adult is not binding upon the minor unless she ratifies (ie. affirms it) the contract after attaining 18 years of age. In effect, the contract is not binding on her and you are better off attempting to remove her under the terms of the agreement and see if she just accepts it and moves out. You will at least be able to rent it to another adult person then.
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