
Quoting
Highwayman
Probation officers do not decide if probation may be ended early, at least in New York they don't. See Criminal Procedure Law 410.90 for more information about early termination of probation.
A motion must be filed with the court. Probation and the District Attorney's Office add their input to process - which means that they will either provide information that will help convince a judge to grant your motion or they may oppose what you're trying to do. The matter then gets calendared in front of the same judge that imposed the sentence of probation, who will then decide what happens.
Since the probation is a sentence of the court, only the court may alter it.
This is hardly a do-it-yourself matter - you need to get a criminal defense attorney involved.