After realizing his mistake, he immediately apologized for retracting his earlier statement.

retracting 是动词 retract 的现在分词形式。retract 由前缀 re-（表示"回、向后"）和词根 tract（来自拉丁语 trahere，意为"拉、拖"）组成，字面意思是"拉回"，引申为"撤回、收回"的意思。retracting 在这里表示"撤回"的动作。