a clean break
From Longman Dictionary of Contemporary Englisha clean breaka clean breakSUDDENLYa complete and sudden separation from a person, organization, or situation Den left the next day, needing to make a clean break. cleanExamples from the Corpusa clean break Why argue about the terms of the divorce when both of you just want a clean break? Gossip has it that his wife had recently left him and he wanted to make a clean break. It was best to make a clean break. Men may suffer just as much when a relationship fails, but they seem able to make a cleaner break. The adoption of an economy based on farming did not effect a clean break. In such cases a clean break at 16+ removed many existing constraints and frustrations. And this year the association has tried to make a clean break from the past. He says it indicates a clean break with a stupid and superstitious past. He made almost a clean break with the game, except for some local television work.