No person shall willfully or maliciously remove, destroy, mutilate or alter the number on any bicycle frame, and no person shall remove, destroy, mutilate or alter any license tag or registration card during the time in which such license tag or registration card is operative, provided, however, that if any bicycle does not have a serial number stamped on the frame, or if such number is illegible, then the Chief of Police shall stamp an identification number on such frame of the bicycle.