clean sweep
1. A large-scale removal of unwanted people or objects to expedite change. In an effort to save the company, the new CEO made a clean sweep and replaced everyone in the finance department. Wow, the garage looks completely different after our big clean sweep!
2. A victory by a large margin, especially one in which the opposing side accumulated none or a very small fraction of the votes, points, etc., required to win. Used especially in politics. The election was a clean sweep for the senator, who won in nearly every county. My team achieved a clean sweep at the national mathematics competition.