After he learned of his cobalt penalty on Thursday, it was Moody's intention to engage David Brideoake as an interim trainer.
But after talking to family, management and close confidantes, Moody realised the Brideoake appointment wasn't workable.
Since he was charged in January last year, Moody said the saga had been financially and mentally draining.
"Last season I ran second to Darren Weir in the premiership, this year I would probably run 22nd," he said.
He said being found not guilty of administering cobalt to affect performance had made his decision to quit much easier.
And Moody is also looking to sell out of the 70 horses that he and his wife share ownership.
"It's an extremely expensive exercise employing lawyers, barristers and solicitors and the reason we did that we believed we did no wrong.
"At the end of the day it cost us a lot of money to be proved not to be a cheat."