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Don't even think about leaving money to your kids — go out and live it up and spend it all, okay?
Literal
Children [to-に] money [object-を] leave-[volitional-よう] [such-a-thing-なんて] not-thinking, whoosh splashily play, use-up please [confirmatory-ね].
Lively life advice delivered with imperative warmth. 残そう is the volitional of 残す ('leave behind'), here the topic of the quoted thought 'let's leave [money for the kids].' なんて attached to a volitional verb 残そうなんて ('something like trying to leave') dismisses the very idea. 考えずに is the literary/formal ~ずに meaning 'without doing X.' パーッと is a 擬音語-flavored mimetic for doing something in a big, splashy, showy way — often associated with spending money or partying. 派手に ('gaudily, flashily, splashily') intensifies the sense. 使い切る ('use up completely') is a compound verb: 使う + 切る ('cut through,' here meaning 'completely, through to the end'). ~てください delivers it as a polite request/instruction.