！
Let's break down our preconceptions!
Literal
Established-concepts [object-を] let's-destroy!
A punchy slogan-style sentence. 既成概念 ('established concepts, preconceptions') is a kango compound — 既成 'already formed' + 概念 'concept.' The plain volitional 壊そう invites collective action. The brevity and exclamation mark give it a rallying-cry energy typical of motivational slogans or advertisements.