Damnatio Memoriae

Damnatio memoriae is the Latin phrase literally meaning "condemnation of memory" in the sense of a judgment that a person must not be remembered. It was a form of dishonor that could be passed by the Roman Senate upon traitors or others who brought discredit to the Roman State. The intent was to erase someone from history, a task somewhat easier in ancient times, when documentation was much sparser.

Read more about Damnatio Memoriae:  Similar Practices in Other Societies, Damnatio Memoriae in Fiction