It was a book that he wrote where he omitted everything with Jesus Christ being the son of god and rather shows him as just a person who wants to do good in the world. I don't know which founding father it is, what the name of his take on the story of Jesus is, or even if it's still in circulation, but I would like to read it and see how much it changes my perception of Jesus.
It sounds like you are talking about what is now commonly known as "the Jefferson Bible." Jefferson called it The Life and Morals of Jesus of Nazareth. However, it isn't a book he wrote, in the sense of composing it. Rather, it is an edition of material from the canonical Christian gospels from which Jefferson removed everything he didn't find appealing or credible, such as miracle stories. He literally cut and pasted it together with a knife or razor and glue. He did not publish it, but he did let various friends see it. The Smithsonian has owned it for a long time now. They have a website about it where you can see images of each page.
You may find that you learn more from it about Jefferson than about Jesus. Since it is simply cut and pasted from a published Bible, if you have read the Christian gospels, there isn't anything there that isn't already familiar.
EDIT: Just to be clear, Jefferson didn't publish it, but others did starting in the late 19th century. It is readily available in several print editions today if you want a copy.