forgive and forget
Both pardon and hold no resentment concerning a past event. For example, After Meg and Mary decided to forgive and forget their differences, they became good friends. This phrase dates from the 1300s and was a proverb by the mid-1500s. For a synonym, see let bygones be bygones.
Examples from the Web for forgive and forget
And after all that, the Burmese Army expects mercy, understanding, forgive-and-forget?Burmese Political Prisoners Speak Out In 'Into The Current' Documentary|Peter Popham|March 28, 2012|DAILY BEAST