wipe the slate clean
US /waɪp ðə sleɪt kliːn/
UK /waɪp ðə sleɪt kliːn/

1.
to forget past mistakes or problems and start again with a fresh outlook
:
•
After their argument, they decided to wipe the slate clean and move forward.
•
The new management promised to wipe the slate clean and address all previous issues.