It shall be unlawful for any person, firm or corporation, to construct, install or maintain or cause to be constructed, installed or maintained on Lincoln Avenue, any awning of wood, sheet iron or other material, which is supported in whole or in part by posts or other supports set into the sidewalk, street or parking. Any such awning as hereinbefore described now existing in the city shall not be repaired or replaced, and when in the opinion of the governing body the same shall be dangerous, they shall be removed.