The city may examine or cause to be examined every building or structure or portion thereof reported as dangerous or damaged and, if such is found to be an unsafe building as defined in this chapter, the city may give to the owner and/or responsible person(s), or both, written notice stating the defects thereof. A responsible person is anyone with managerial authority over the building, including managers, trustees, executors and settlors of trusts. The notice may require the owner and/or responsible person(s), within 48 hours or such reasonable time as the circumstances require, to comment either the required repairs or improvements or demolition and removal of the building or structure or portions thereof, and all such work shall be completed within 90 days from date of notice, unless otherwise stipulated by the city. If necessary, such notice may also require the building, structure, or other portion thereof to be vacated forthwith and not reoccupied until the required repairs and improvements are completed, inspected, and approved by the city.