"She was let go," a show insider told People. "Producers were sick of her constant tardiness and her issues."
However, a Maloof source argued she opted to call it quits herself.
"It was her decision to leave. Adrienne is very happy. The producers were begging Adrienne to come back to the show and the reunion right up until the last minute," said the source. "Housewives was part of her past. She's looking to the future."
Maloof's exit is reportedly part of the producers' attempt to shakeup the fourth-season cast.
Maloof also reportedly didn't make an appearance on The Real Housewives of Beverly Hills' recently taped third-season reunion show due to her divorce from new ex-husband Dr. Paul Nassif that was finalized in early November.