Anyone can have any charges dropped if the offence never occured, but it is all evidentially based. I doubt charges would arise without evidence?
The sex offenders register, not list, is a higly contentious piece of legislation insofar as people who drunkenly urinate in the street have been added to it and, in my humble opinion, this in no way correlates to people who abuse children. It was a hurriedly rushed knee-jerk reaction to one of the worst crimes possible.