Oh, IDK, use words maybe? Coersion, public shaming, ignoring, detention, suspension, taking away privileges, assigning additional work, moving her into the hallway, perhaps moving the entire class outside and shutting the lights off on her. Can they drive to school? Take away parking privileges. Is she in sports? Suspend from team. To name a few... Get creative, don't get violent.
Words: She was asked to leave several times by different people.
Coercion: The cop told her to move or he was going to move her.
Public shaming: I am not sure school can do that to a student, but I am for it.
Ignoring: Ignoring the problem doesn't make it go away, plus it give the student the power.
Detention/Suspension: I think that was a given when she was told to leave and the principle came in. If you told to go to the principle's office that normally means you got detention or worse.
Privileges: Not a lot of privileges to take from a student unless you plan to force the parents to ground her.
More work: That she probably wouldn't do, then we are back to square one.
Move her to the hall: They tried to move her out of the desk and she resisted. Pretty sure she was going to resist any movement forced upon her.
Move the class: So, the student wins? Sets very bad example.
Parking / Sports: Doesn't solve the problem at hand, which was she was not leaving when told to.
When some really doesn't want to move, but you want them moved now force is required. Could he have been gentler sure. But, I don't think he was trying to hurt her or she would be really hurt. Also it is against the law in SC to disrupt class and you can be arrested for it. So, don't act up in class in SC and nothing will happen.