How do I reorder or delete an object in a stack?

This must be done inside of the Mapmaker and is not currently possible in Builder Mode while you are inside of a Space. 

You can rearrange and re-prioritize how the the objects are viewed  in any given tile by dragging and dropping the objects on the right side object list panel inside of the Mapmaker. The object you  have highlighted on the right panel is the currently selected object that you can drag and drop to rearrange the order of the objects on that square grid. 

Editing an Object Stack

Delete Object

To delete a single object, drag the object you would like to delete out of the stack of objects into a square that does not have other objects. Switch to Object Erase Mode and select the object again. 

Make sure you are in Object Eraser mode by having both the object icon and eraser icon highlighted in the upper left of your screen.