Claude Myers, 54, who has 46 prior arrests and is on parole, allegedly unzipped the unsuspecting victim’s backpack and withdrew $60 on Thursday at about 5 p.m. inside the Lexington Avenue-63rd Street station, according to a law-enforcement source and court papers.

Myers didn’t realize that a plainclothes transit cop was watching nearby. He allegedly saw Myers count the three twenty dollar bills then slip them into his wallet.

Police arrested him on charges of grand larceny in the 4th degree for removing the property from a person, criminal possession of stolen property and possession of a controlled substance after recovering a clear container with synthetic cannabinoid from his pocket.

But when prosecutors wrote up the complaint against Myers, the top charge was downgraded from felony grand larceny to petit larceny, court records show. Judge Michael Gaffey ordered Myers released without bail.