He said he didn't consider speaking up until he heard about last week's accusation.
"I thought I was a unique circumstance," Singleton said. "I did not know that it was something he had done habitually."
Singleton's lawyer, Jeff Herman, said he had been contacted by two other potential victims and expects additional legal action. Sex with a person under 17 is a felony in New York if the perpetrator is 21 or older.
Elmo has been a major moneymaker for Sesame Workshop. By one estimate, Elmo toys, such as the giggling Tickle Me Elmo doll, account for one-half to two-thirds of the $75 million in annual sales the Sesame Street toy line generates for Hasbro.
Clash became something of a star himself. In 2006, he published an autobiography, "My Life as a Furry Red Monster," and he was the subject of the 2011 documentary "Being Elmo: A Puppeteer's Journey."
Episodes with Clash performing as Elmo will presumably continue well into 2014. Taping of season No. 44 will wrap by mid-December and will begin airing next September, according to someone close to the show who spoke on condition of anonymity because the person was not authorized to publicly discuss details of its production.
As for who might take over as Elmo, other "Sesame Street" puppeteers have been trained to serve as Clash's stand-in, Sesame Workshop said.
"Elmo is bigger than any one person," the company said last week.
On Tuesday, Hasbro echoed that sentiment with its own statement: "We are confident that Elmo will remain an integral part of Sesame Street and that Sesame Street toys will continue to delight children for years to come."
AP Television Writer David Bauder and AP Retail Writer Mae Anderson contributed to this report.