Establishers are individuals or entities that create, set up, or initiate something new. However, if we talk about antonyms for establishers, we can think of those who disrupt, dismantle, or abolish something that already exists. For example, the antonym for an establisher who sets up a new business could be someone who liquidates a business. Similarly, the antonym for an establisher who establishes a government could be someone who brings down an existing government. Other antonyms of establishers could include destroyers, dissolvers, undoers, disrupters, disbanders, and annihilators. These individuals or forces work towards destabilizing and shaking up established systems rather than creating them.