“A memory hole is any mechanism for the alteration or disappearance of inconvenient or embarrassing documents, photographs, transcripts, or other records, such as from a web site or other archive, particularly as part of an attempt to give the impression that something never happened.
Current usage
A memory hole is seen by some as one of the common tactical and strategic operations of governments, particularly as a method of silencing those whose historical views are out of step with governmental or more popular views. As two seminal quotations note: “Who controls the past controls the future. Who controls the present controls the past.” — Inner Party member O’Brien in 1984; “Every government is run by liars and nothing they say should be believed.” — I. F. Stone”
serge 
Good stuff, for sure.