From Longman Dictionary of Contemporary Englishwipe the slate cleanwipe the slate cleanSTART DOING somethingto agree to forget about mistakes or arguments that happened in the past → wipe
Examples from the Corpus
wipe the slate clean• First among these was the introduction of penances which, it was hoped, would wipe the slate clean.• It would be nice if we could wipe the slate clean and start over.• We must start wiping the slate clean of all such inner accounting. 