It shall be the duty of the owner, lessee, occupant, or person having the control or custody of any premises or unimproved property to remove all snow or ice which has fallen or has accumulated upon the sidewalks abutting upon such premises or property within two hours after such snow or ice has ceased to fall thereon; provided, however, that if such snow is falling or such ice accumulating after the hour of six p.m., the same shall be removed within two hours after it shall cease to fall or within two hours after seven a.m. on the next succeeding day, as the case may be. (Ord. 15 § 66, 1954.)