Antonyms for the word "stacking up" are disorganizing, decluttering, scattering, and dispersing. Disorganizing means to disturb the arrangement of something, whereas decluttering refers to removing an unwanted or unnecessary item from a space. Scatter implies to spread out something in different directions, and dispersing is equivalent to the act of scattering out. While stacking up refers to piling up objects or information in a neat manner, its antonyms are about separating or spreading things. So, to keep space in order, you need to disorganize or declutter the things that pile up, and scatter or disperse them into a place where they can be easily accessed.