The phrase 'took the reins' implies taking control or taking charge of a situation. Some possible antonyms for this phrase include giving up control or relinquishing power, backing down or retreating from a leadership role, deferring to someone else's authority or expertise, or simply remaining passive or disengaged. Antonyms might include phrases like 'yielded the floor', 'deferred to leadership', 'abdicated responsibility', 'took a back seat', or 'left it to others'. Depending on the context and the speaker's intent, these antonyms could convey a sense of humility, collaboration, or indecisiveness.