Around one year ago, Azaria met with The Simpsons bosses Al Jean, James L. Brooks, and Matt Groening to tell them he no longer wanted to voice Apu. He said the executives were "very sympathetic and supportive" when he told them he was "uncomfortable" voicing Apu.
Azaria went on to say that he still loves The Simpsons and he hopes to continue to be a part of it for a long time to come. Azaria also voices Moe, Chief Wiggum, Comic Book Guy, Cletus, Professor Frink, the Sea Captain, Superintendent Chalmers, Disco Stu, and Duffman, among others.

The Simpsons Apu Controversy: Hank Azaria Explains Why He Will No Longer Voice The Character
The veteran voice actor says he initially bristled at controversy but he eventually decided "it just didn't feel right" to continue.
I'm a total Simpsons fan and have been since they started on the Tracey Ullman show..... I actually find Azaria's decision slightly weird as all the characters on the show are stereotypes of sorts.