Answer:
Susan has the right to disaffirm because by law she is minor and at such any contract she signs which does not include essential needs such as medicine, food and medical services is not binding and at such she can void the contract at any time.
Erin cannot force her to honor the contract since the contract was not signed with the aid of an adult.
Explanation:
Minors are not allowed to sign a contract without the aid of an adult unless it is for their essential needs such as medical cases or food.