Okla. Stat. tit. 51 § 8
Every office shall become vacant on the happening of any one of the following events before the expiration of the term of such office:
First. The death of the incumbent or his resignation.
Second. His removal from office or failure to qualify as required by law.
Third. Whenever any final judgment shall be obtained against him for a breach of his official bond.
Fourth. Ceasing to be a resident of the state, county, township, city or town, or of any district thereof, in which the duties of his office are to be exercised or for which he may have been elected or appointed.
Fifth. Conviction in a state or federal court of competent jurisdiction of any felony or any offense involving a violation of his official oath; provided, that no conviction, as a cause of vacation of office, shall be deemed complete so long as an appeal may be pending, or until final judgment is rendered thereon.
Sixth. Upon entering of a plea of guilty or nolo contendere in a state or federal court of competent jurisdiction for any felony or any offense involving a violation of his official oath.
The fact by reason whereof the vacancy arises shall be determined by the authority authorized to fill such vacancy.
Okla. Stat. tit. 51, § 8