It shall be unlawful for any person to wilfully or maliciously remove, destroy, mutilate, or alter the number of any bicycle frame licensed pursuant to this chapter. It shall also be unlawful for any person to remove, destroy, mutilate, or alter any seal or registration card, during the time in which the seal or registration card is operative; provided, however, that nothing in this chapter shall prohibit the fire department from stamping numbers on the frames of bicycles on which no serial number can be found, or on which the serial number is illegible or insufficient for identification purposes. (Ord. 1019, 12-12-1972; amd. Ord. 1052, 2-12-1974)