Criminal Law Questions? Ask a Criminal Lawyer.
Basically just file a request with the judge who put you on supervised release to amend the supervised release to time already served. Explain to the judge why you feel you should be granted early termination. Just be aware if you were sentenced to supervised release for a crime that has a mandatory minimum of five years, you can't get early termination. But if five years was the time the judge came up with, then you can try.