qnli question: For what event was the largest amount of signatures collected in an attempt to keep Kanye from performing at it? sentence: On July 20, 2015, within five days of West's announcement as the headlining artist of the closing ceremonies of the 2015 Pan American Games, Change.org user XYZ collected over 50,000 signatures for West's removal as headliner citing the headlining artist should be Canadian.