He said they have no plans to record anything else, or have the kids make any more public appearances.
"We know the kids involved have had a wonderful experience, but we think this chapter is now done, and we want these kids to get back to being kids," he said.
Copies of their version of "Over the Rainbow" are being sold on Amazon and iTunes.
The proceeds from the download of the single benefit the United Way of Western Connecticut and the Newtown Youth Academy. The nonprofit sports center opened free programs to Newtown children after the shooting and hopes to expand free programming.
The Grammy performance follows Sunday's appearance by another group of Newtown children at the Super Bowl.
Jennifer Hudson joined a chorus from Sandy Hook Elementary School to sing "America the Beautiful" before the game. The emotional performance had some players on the sideline on the verge of tears.