At the end of IT: Chapter 2, after the clown fatally stabs Eddie, the Losers Club gang up on Pennywise and essentially insult him to death. The scene’s intended purpose is to illustrate the fact that the Losers Club needed internal strength, not psychical power, to overcome the villain.

In the final showdown between the friends and Pennywise, they group discovers that belittling the murderous clown is a weakness, and cause him to decrease in size. They taunt him until he shrinks down extremely tiny and is incapacitated by his feebleness.

In King’s novel and IT: Chapter 2, the adult Losers go to IT’s lair in the sewers of Derry to confront it one last time, and after some tragic events, such as Eddie’s death (in the novel, IT bites his arm off – in the movie, he’s impaled by the creature), they take out IT’s heart – who, by then, had already transformed into a giant spider – and crush it, seemingly killing the creature for good.