2016 Wesleyan Discipline: 4520
From Wesleyan Discipline
4520. A trustee must be a Wesleyan Church member who meets the leadership qualifications (2016 Wesleyan Discipline:260–268; 2016 Wesleyan Discipline:558). Whenever a trustee ceases to be a member with said qualifications for any reason, the office as trustee shall be declared vacant and a successor shall be elected for the unexpired term in the manner provided in The Discipline.