Write a long, nasty, mean-spirited letter to explain everything that they dislike about the church and articulate their own self-pity at length. Entering into, engaging with, and departing from Christ's local body is a significant part of following Jesus.Communicate clearly and graciously. I recommend doing this in person, on the phone, or through a thoughtful, personal email. If people are gracious enough to let me know they are leaving, I write them a letter and thank them for their attendance and past service. Try to leave graciously. Supplement to the ministers widows scheme, in a letter to the clergy, directing the improvement of their glebes.