不咎既往

to forget and not bear recriminations (idiom); to let bygones be bygones; There is no point in crying over spilt milk.

do not recall old grievances (idiom, from Analects); forgive and forget

to overlook past faults (idiom); to forgive and forget

to forget former enmity (idiom)

to forget previous differences; to bury the hatchet

to repent and start afresh (idiom); to turn over a new leaf