How did the movie IT end?

In the movie "IT" (2017), the Losers' Club confronts Pennywise in the final battle in the sewers beneath Derry. They realize that Pennywise is vulnerable when they confront their deepest fears and unite against him. After a fierce struggle, they manage to weaken Pennywise by declaring their fearlessness, ultimately leading to his defeat. The film ends with the group promising to return if Pennywise ever resurfaces, while they begin to move on with their lives as adults.