reverse (one's) course
1. To stop and begin moving in the opposite direction. The quarterback tried reversing his course to evade the defensive linesmen, but he wasn't quick enough and ended up getting sacked in the end zone. As soon as we saw the family of bears, we quietly and hastily reversed course.
2. To suddenly hold or profess a position or opinion that runs contrary or opposite to one held previously. The senator seemed to reverse course the following day, stating that he would never condone police violence against any citizen. The city's legal team spent months convincing the judge to reverse her course and allow the case to proceed.