It shall be unlawful for any person to erect or repair over any sidewalk or street any wooden shed or awning or any wooden shed for the support of an awning, or erect upon any street or sidewalk any post for the support of any awning. If any person shall violate this section, then each day that the above forbidden obstruction shall remain, after notice, shall constitute a separate violation of this section; provided, that this section shall not be construed to prevent the erection over the sidewalk of cloth awnings, supported upon metallic frames, firmly suspended from the building; provided further, that the City Manager shall have the power to condemn and order removed any wooden awnings now existing when they shall become dangerous or unsightly or in any way detrimental to the public health or public safety of life and limb.