I've had several friends who simply moved away from their home congregation. When they left they told no one or indicated that they would send a forwarding address as soon as they were permanently set in at their new town or state.
Usually appearing to stay active right up until your move works best. If you've already broadcast your intention to leave by only attending meetings occasionally and not otherwise participating, everyone will figure that you are bailing and will then come after you.
The smoothest transition I ever saw was back in the mid-1980s when an elder and his family decided they wanted out. He had an opportunity to get a better job in a city some distance from his old home. As he and his family left their home congregation for the last time, they told everyone that they would send their address to one of the other elders and let everyone know how they were doing. When asked where they were moving, they replied along the lines of "northern Washington, but we don't have a permanent address yet." In those days no one had cell phones, so telephone numbers did not follow them. (You can do the same thing by changing carriers at the same time you move and only inform those who you trust with your new numbers.)
No one will give much thought about you for the first few months. But then when no request for your publisher's records arrives, the elders might think something is up - but most are lazy and will just let it ride for a while.
Do not contact anyone you left behind. If you do send a note, use email or send a card with no return address and maybe a message like, "We're still looking for a permanent place up here in northern Washington."
It worked for them. Just fade into the distance. They will forget all about you unless you leave relatives behind. Don't leave relatives behind...