The series' judge and executive producer, real-estate mogul Donald Trump, fired Warwick after she went home while her teammates worked on their assigned challenge of making a TV commercial, E! News reported.
Warwick, 70, said she wanted to fire herself when she got to Trump's boardroom, then changed her mind and said she wanted to continue competing.
"Dionne, it wasn't that simple. You did leave and I'm not certain that you asked the project manager for approval," Trump told Warwick on Sunday night's episode of the business-themed series. "It almost seems like you think everyone is against you … . Honestly, it's too late. It's really too late. You did the wrong thing. Dionne, you're fired."
Still in the running are La Toya Jackson, Star Jones, Gary Busey, Meat Loaf, Hope Dworaczyk, NeNe Leakes, Marlee Matlin, Jose Canseco, Richard Hatch, Lil Jon, Mark McGrath and John Rich.
Former teen idol David Cassidy, actress Lisa Rinna and model Niki Taylor were eliminated earlier this season.