Okla. Stat. tit. 19 § 865.55
The commission shall consist of three (3) members appointed by the board of county commissioners and the chairman of the board of county commissioners or a member of the board of county commissioners appointed by the chairman and one member to be appointed by the mayor of each incorporated city or town having a population of one thousand or more according to the last federal census. Members appointed by the board shall serve a term of four (4) years, except that the respective terms of the first three appointed shall be for terms of four (4) years. All members of the commission shall serve as such without compensation. Each appointed member shall be a resident of the area included within the jurisdiction of the commission for a period of three (3) years or more immediately preceding appointment and shall hold no other municipal or county office. Vacancies occurring otherwise than through the expiration of term shall be filled for the unexpired term.
A member of such commission, once qualified, can thereafter be removed during his term of office only for cause and after a hearing held before the governing body by which he was appointed.
Okla. Stat. tit. 19, § 865.55