Dedicating oneself to something means committing oneself to a cause or goal. Antonyms for the phrase would include disengaging, giving up, and neglecting. Disengaging would suggest separation or detachment from something previously pledged, perhaps from a relationship or job. Giving up would suggest abandonment or surrender of a project or belief. Neglecting would indicate a lack of attention or care, implying that the thing being left behind is of minimal importance. It is important to note, however, that a lack of dedication or commitment to something does not necessarily imply any of these negative connotations, as priorities and values can shift over time.