"Kicking over the traces" is an idiomatic expression used to describe someone who is challenging authority or breaking the rules. There are several synonyms that can be used in its place, including "rebelling," "defying," "disobeying," "flouting," or "contravening" authority. Other synonyms for this phrase can be "going rogue," "resisting control," "revolting," "insubordinate," or "mutinous." These words all convey the idea of challenging authority or disregarding rules. It is important to choose the appropriate synonym for the context of your writing, as some may carry a stronger connotation than others.