The chief of police shall have general supervision over all city property, and he and his subordinates shall have authority to arrest any trespasser on city property or portions thereof not open to the public or trespassers on property open to the public during certain specified times but who are thereon during times when such property is closed to the public, and to remove or abate nuisances or encumbrances put thereon without the authority of the city.

(Code 1964, § 7.255)