On Friday, the Counter Extremism Project, an advocacy group based in Washington, called on YouTube and other platforms to permanently ban Mr. Awlaki’s material, including his early, mainstream lectures.

“His work has inspired countless plots and attacks,” said Mark D. Wallace, a former diplomat and homeland security official who is the project’s chief executive. “It’s hate speech. It should come down, period. Like child porn, it should be expeditiously removed.”

Mr. Wallace said the ban should cover not just violent jihadist material, but anything Mr. Awlaki recorded, including such popular works as his 53-CD set of lectures on the life of the Prophet Muhammad, widely excerpted on YouTube and other sites. Though not objectionable in itself, Mr. Wallace said, such material adds authority to the cleric’s later calls for violence.

“There are a lot of sources for the teachings of Islam that do not come from a man who became one of the world’s most notorious terrorists,” he added.