Bob McGrath — one of the longest-running characters in TV history, essentially playing himself as “Bob,” the music teacher, on “Sesame Street” — has left the children’s TV classic, he confirmed on a podcast streamed earlier this week. In addition, he said other long-running cast members, Emilio Delgado (Luis) and Roscoe Orman (science teacher Gordon) — both of whom joined in the ‘70s — had also been let go.

“I have completed my 45th season this year,” McGrath, 85, said during the podcast, titled “Muppetcast.” “And the show has gone under a major turnaround, going from an hour to a half-hour. HBO has gotten involved also. And they let all of the original cast members go.”

Loretta Long (“Susan”), who like McGrath joined “Street” even before the Nov. 10, 1969, launch when she appeared in four early test shows, was not part of the cast reduction, according to reports.

McGrath’s comments appeared to catch both PBS, which lost “Sesame Street” to HBO last fall, and the show’s producer, Sesame Workshop, off-guard.

PBS president and CEO Paula Kerger told television critics at the TV Critics Tour in Beverly Hills on Thursday, “As you know, ‘Sesame Street’ is produced by Sesame Workshop, which is an independent production company, and the casting decision was made by them. We did not know about it beforehand. We found out about it after.”

However, after a backlash on social media Thursday, Sesame Workshop released a statement indicating the cast members would continue with the series in some capacity. The three “remain a beloved part of the Sesame family and continue to represent us at public events,” the statement said, adding “our cast has changed over the years, though you can still expect to see many of them in upcoming productions.” It also said HBO had no role in the changes: “HBO does not oversee the production.”

A spokesman for Sesame Workshop said in an email, “All three of them continue to appear in segments on the show — including in our upcoming season 47. As you may know, from the very beginning, Sesame Street has a tradition of re–airing content because we’ve found that repeated viewings deepens the educational impact for children.”

While the human cast members, or notably the originals, have had their appearances cut back in recent years — a reason Sonia Manzano (“Maria”) said she left the show after a 44-year run in 2015 — such a wholesale cost reduction on “Sesame Street” is unprecedented. McGrath hasn’t appeared as “Bob” since 2014, according to IMDb, while “Street” now airs in a half-hour format on HBO.

McGrath, a professional singer who got his start on the old NBC hit show “Sing Along with Mitch,” and later became a singing star in Japan — where he sang American standards and popular Japanese songs in flawless Japanese — was hired along with Will Lee (“Mr. Hooper”), Long and Matt Robinson (the original Gordon). Robinson died in 2002, and Lee in 1982.

McGrath said in his “Emmy Legends” interview taped in 2004 that the part he auditioned for was written for “‘Bob,’ and I said ‘Who do you want me to be?’ They said they weren’t sure and so through the years, I was the music guy, doing a lot of singing and working with Joe Raposo and Jeff Moss (“Street’s” legendary composers and lyricists in the early years). Ultimately, (producers) said, we don’t want you to be anybody else — we want you to be yourself.”