The term "building up on" implies a gradual increase or accumulation over time. Its antonyms, on the other hand, refer to various ways of reducing or removing the same accumulation. For instance, breaking down, tearing down, and demolishing all involve reducing the size or quantity of what has been built up over time. Similarly, reducing, decreasing, and eroding can all be used to describe a process of reducing the amount of buildup or growth. Conversely, antonyms such as conserving, guarding, and protecting suggest ways of preventing further accumulation or growth. Whether you're trying to reduce, remove, or prevent buildup, there are many antonyms available to help you achieve your goals.