As long as you are a willing member of a religion you are subject to that religions in house ecclesiastic authority . JW baptism confirms your cult membership.
Freedom of Religion laws give rights to both those who practice religion and those who wish to leave a religion.
Since religious activity is a personal and voluntary activity there are no legal requirements that need to be met to join, explore, change or abandon any religion.
Your acceptance of ecclesiastic authority "Started" when you chose to be baptized. and, until you engineer a defining "Stop" you are viewed as a member.
The good news is you aren´t legally required to inform anyone at all about your decisions in this voluntary/personal enterprise. Nor give reasons, or write letters or meet with elders - but you do have to stop being a JW to stop being treated as one.
Ecclesiastic authority applied to former members would then violate ones freedoms of religion