The producers follow judges Mariah Carey, Nicki Minaj and Randy Jackson out the door.
Fox confirmed the producers' departure after Lythgoe said online that he'd been "fired" from the show.
"It's not a personal thing," he said in a posting Saturday on his Twitter account. "They just feel IDOL needs new leadership after 12 Seasons."
Jackson was an original panelist. Minaj and Carey joined this season, and their on-air bickering proved uncomfortable for viewers and contestants.
The fate of Keith Urban, the other newcomer, is uncertain, and Fox didn't announce who would replace the producers.
In a statement, Fox and the companies behind "American Idol" thanked Lythgoe and Warwick for their work and said they looked forward to working with them on other projects.
Lythgoe is the producer and a judge for Fox's "So You Think You Can Dance."
The network "still loves me," he tweeted.