In Florida a homeowner can remove a guest through Florida Statue 82.03 which says the Remedy for unlawful entry and forcible entry.�If any person enters or has entered into lands or tenements when entry is not given by law, or if any person enters or has entered into any lands or tenements with strong hand or with multitude of people, even when entry is given by law, the party turned out or deprived of possession by the unlawful or forcible entry, by whatever right or title the party held possession, or whatever estate the party held or claimed in the lands or tenements of which he or she was so dispossessed, is entitled to the summary procedure under s. 51.011 within 3 years thereafter.
You start this by giving your son written notice to leave, then filing a complaint and serving it on your son and then setting a hearing to get an Order or Writ to be served by the Sheriff and remove your son.
My law firm does this type of action if you need further questions answered. Bates-Buchanan and Savitsky Law Group, 941-799-3015