Regardless of whether or not someone wants to de-crow a rooster or not, it's going to require the surgical prowess of a veterinarian to actually pull it off. Your best bet is going to be talking to a vet who is experienced with poultry; see what they tell you. I'd be doubtful that many would be willing to do this - just not worth the risk of causing permanent eating/drinking/breathing problems for the bird, or the stress it would place on the bird to perform.
If she can't have roosters where she is at, then she shouldn't get roosters, or should move to a location where she can have them. I can't see the logic behind cutting up a bird in an attempt to prevent it from doing what its meant to do for the sake of conforming to a local ordinance.
