I was also an elder and I tried to figure out how I could resign.
One day I told my wife that due to doubts I have I can no longer be an elder. I called the Cobe and wrote a letter of resignation due to doubts.
I had to explain everything to the CO and then it was such a liberating feeling not being an elder anymore. Like a huge wheight lifted from my shoulders.
Over about 1 year the elders tried to reason with me on my doubts afterwards. But if you stand firm they will loose the interest.
When I look back I gave them too much authority. I should have said. My faith is between me and Jehovah. There is no need for lengthx discussions.