Chronotereletion 

Chronotereletion is the process of which a thing, such as a word, idea, event, etc., is forgotten through time. It also is the process of which a thing is forgotten through the use of force or repression.

As whatever could be used as an example is forgotten, it's not quite simple to provide a specific example. A more generalized example would be in the novel 1984, where the history of the society is often changed into falsehoods by the government, thus leaving the real history left behind and forgotten. That would be a good example of both of the definitions of chronotereletion.

Chronotereletion by Student Who Did His Assignment February 21, 2014