The 19-year-old French midfielder has made two substitute appearances for the Cumbrians since joining them in October.
Carlisle manager Greg Abbott told the club's official website: "Jeremy had a good month with us and Manchester City were really happy with the way we did things, but it appears that something else has come up for him.
"We spoke to him and told him that we wanted him to stay and City had also agreed a deal for that to happen, but you have to respect the player and his wishes.
"What I can say is that he has worked extremely hard and it has been a pleasure for us to have him. We'll see where he goes now, because he has kept that close to his chest, but he leaves with our very best wishes."