What event occurred on November 9, 1989, ending a powerful symbol of Soviet repression?

the tearing down of the Berlin Wall

The correct answer to the following question will be "The Fall of the Berlin Wall".

Explanation:

The collapse of the Berlin Wall on 9 November 1989 marked the fall of the Iron Curtain and the beginning of communism in Central and Eastern Europe. The spokesman for the Communist Party of East Berlin declared a transition to his city's trade relations on November 9th, 1989, when the Cold War started to twine in Eastern Europe. He said that people of the GDR were free to cross the borders of the country, starting at midnight that day. On 3 October 1990, almost one year after the fall of the wall, the reunification of Eastern and western Germany was announced officially.

Therefore, The Fall of the Berlin Wall is the right answer.