The board of a school district may dismiss a school district superintendent prior to the expiration of the individual's contract for any of the following causes:
1. Immoral conduct.
2. Insubordination.
3. Conviction of a felony.
4. Conduct unbecoming the position of superintendent.
5. Failure to perform contracted duties without justification.
6. Gross inefficiency that the superintendent has failed to correct after written notice.
7. Continuing physical or mental disability that renders the superintendent unfit or unable to perform the superintendent's duties.