This letter can be sent when a club member is no longer willing or able to continue in a leadership role.
Dear Ms. Clubleader,
I wish to immediately withdraw my membership in (club). I can no longer continue due to (injury/ethical issue/residency). Obviously, this means I won't be serving the leadership role of (role).
In light of this situation, I would like to request a refund of my outstanding dues in the amount of (amount). A check can be mailed to: (address).
I do have one suggestion regarding the club: (suggestion). I hope that you will take it under advisement.