"I am resigning from Sesame Workshop with a very heavy heart," Clash said in a statement. "I have loved every day of my 28 years working for this exceptional organization. Personal matters have diverted attention away from the important work 'Sesame Street' is doing and I cannot allow it to go on any longer. I am deeply sorry to be leaving and am looking forward to resolving these personal matters privately."
The puppeteer's resignation comes immediately after he was hit with a lawsuit by a second accuser, Cecil Singleton. The aspiring model claimed he was only 15 when he started a sexual relationship with Clash.
"I was sexualized at a very early age," Singleton said at a news conference.
Singleton says he met Clash on a gay phone chat in 2003. He has filed a lawsuit seeking damages in excess of $5 million.
"Many of you, I'm sure, may question my motive for waiting a near decade before coming forward," Singleton said. "The truth is, in retrospect, it has occurred to me as an adult how truly inappropriate my relationship with Kevin was."
In his lawsuit, Singleton alleges he suffered adverse psychological and emotional effects from the relationship. Clash has not commented specifically on Singleton's allegations.
In a statement, the company that produces "Sesame Street" said, "Unfortunately, the controversy surrounding Kevin's personal life has become a distraction that none of us wants, and he has concluded that he can no longer be effective in his job and has resigned from 'Sesame Street.' This is a sad day for 'Sesame Street.'"
Clash took a leave of absence last week following allegations that he had an inappropriate relationship with a 16-year-old boy. That accuser, now 23, later recanted his claim in a statement, saying he was actually 18 and that it was consensual.
The Associated Press contributed to this report.