The directors of such schools shall have full power and authority, pursuant to the adoption of such rules and regulations made and adopted by them, to suspend or dismiss any pupil or pupils of such schools therefrom, or to prevent them, or any of them, from graduating or participating in school honors when, after investigation, in the judgment of such directors, or a majority of them, such pupil or pupils are guilty of violating any of the provisions of section 287.1, or are guilty of violating any rule, rules, or regulations adopted by such directors for the purpose of governing such schools or enforcing said section.