The book that is destroyed in the story is a copy of "The Scarlet Letter" by Nathaniel Hawthorne, which Jerry is carrying to a class. This act of vandalism is orchestrated by the "Vigils", a secret society at Trinity High School, who are trying to force Jerry into selling chocolates to raise money for the school.
The destruction of "The Scarlet Letter" is a symbolic act, representing the Vigils' attempt to suppress Jerry's individuality and independence.