(a) because at the time of his appointment he was ineligible or has since become ineligible to hold such office; or

(b) for malfeasance or nonfeasance in office; or

(c) upon conviction of a felony or of a misdemeanor involving moral turpitude; or

(d) for failure to perform the duties of his office in an honorable, competent and reasonably efficient manner; or

(e) if he becomes morally, physically or mentally unfit to act in behalf of the county. 4. Before an appointive county executive can be removed, he must be given ten days' written notice of the proposed action, and if he so demands, must within ten days after such demand, and at least ten days before the board of supervisors votes to remove him, be furnished with a written statement of the charges against him or the reasons for his removal in order that he may reply thereto. If he so demands within five days after receiving such statement or at any time prior thereto, he shall also have the right to a hearing on such charges or reasons arranged with at least five days' public notice at a public meeting of the board of supervisors held within fifteen days of such demand and the board of supervisors shall not vote on the question of his removal until at least ten days after such hearing. Pending removal, the board of supervisors may suspend him from office, except that the period of suspension shall not exceed fifty days. The action of the board of supervisors in suspending or removing a county manager shall not be subject to review. Such action in suspending or removing a county executive other than a county manager shall be subject to review under article seventy-eight of the civil practice law and rules.