The term of the member composing Class I shall correspond to his or her official tenure as Mayor. If the Mayor designates a person to sit in the absence of the Mayor, that person shall serve at the pleasure of the Mayor. The terms of the members composing Class II and Class III shall be for one year or terminate at the completion of their respective terms of office, whichever occurs first, except for a Class II member who is also a member of the Environmental Advisory Committee. The term of a Class II or Class IV member who is also a member of the Environmental Advisory Committee shall be for three years or terminate at the completion of his or her term of office as a member of the Environmental Advisory Committee, whichever comes first. The term of a Class IV member who is also a member of the Zoning Board of Adjustment or City Board of Education shall terminate whenever he is no longer a member of such other body or at the completion of his or her Class IV term, whichever comes first. Thereafter, the Class IV term of each such member shall be for four years. If a vacancy in any class shall occur otherwise than by expiration of the Planning Board term, it shall be filled by appointment, as above provided, for the unexpired term. No member of the Planning Board shall be permitted to act on any matter in which there is any personal or financial interest, either directly or indirectly. Any member other than a Class I member, after a public hearing, if requested, may be removed by the governing body for a cause.