walk back something
phrasal verb with walk verb uk/wɔːk/ us/wɑːk/
改变（意见）;收回（说法）
to change an opinion that you had expressed before or admit that a statement you made was wrong
He has since walked back his opposition to the bill. 此后，他收回了对该法案的反对意见。
With massive video evidence, he walked back his claim that he was spat on. 在大量的视频证据面前，他收回了有人朝他吐口水的说法。