！
Scrap the 24-hour operation of convenience stores to save energy!
Literal
Energy-conservation [for-のために] convenience-store [genitive-の] 24-hour business [object-を] abolish!
A plain-form imperative in slogan/protest register. 廃止しろ is the bare imperative of 廃止する ('to abolish'). The plain imperative is blunt and rarely appropriate in polite contexts, but it's the natural choice for signs, slogans, protest chants, and shouted commands. ~のために ('for the sake of X,' 'in order to X') marks the purpose clause — here, energy conservation is the reason for the demand. The compound noun 省エネ is the clipped form of 省エネルギー ('energy-saving') — the kind of katakana + kanji mashup common in bureaucratic and eco-conscious vocabulary.