In the event any officer or employee be found guilty of (a) violating any ordinance of his city or law of the State or any rule or order of the commission or city council pertaining to his work or conduct or the conduct of the department of which he is an officer or employee, (b) insubordination to the commission or his superior officer, (c) disrespectful conduct toward the mayor of the city or any of its councilmen, (d) conduct unbecoming an employee of the city or his department, (e) conduct which might bring discredit upon or disrepute to the city or his department, (f) inefficiency or (g) oppressive use of his authority, the commission may dismiss or discharge him from service, demote him in rank, fine him not exceeding thirty days’ pay or withdraw his vacation privileges.