Since this is a lose-lose situation I personally composed a brief letter citing the very specific reasons as to why I was leaving the organization and I sent it to every single Jehovah's Witness I know. Everyone except my Elders, ONLY the rank and file JWs that I knew received my letter.
The entire disassociating process is a set up, you aren't meant to walk away clean no matter what.
I personally wouldn't bother composing a letter to send to Bethel Headquarters or to your body of Elders. The best solution is to do the unexpected. Ignore Watchtower protocol and reach out to everyone on an individual level instead of submitting yourself to character assassination by way of rumors. Let there be no doubts as to why you left. The vast majority may ignore it but the one or 2 people that do read it will be grateful someday. This is all assuming you can afford to do something like this of course.