Final answer:
A legal guardian or responsible parent in Florida can cancel a minor's driver's license by submitting a written request, leading to the license being canceled until another adult assumes responsibility.
Step-by-step explanation:
In Florida, if a legal guardian or responsible parent who signed an underage driver's license application decides to withdraw their responsibility, the minor's driver's license will be canceled. The legal guardian or parent would need to submit a written request to the Department of Highway Safety and Motor Vehicles to have the license canceled. Until a new responsible adult is willing to assume the liability, the minor's ability to legally drive is put on hold.