As said previously, NaroCAD changed slightly the delete behavior. The old behavior was like following: any shape you delete, it will delete itself and all impacted, shapes. For example if you removed a sphere that is a part of the result of a Boolean operation, both sphere and the Boolean shapes were removed.
The new behavior will be two steps operation: hide from tree and from scene and if is not reachable, will be removed and with all related shapes that may also become unreachable. So in this way, if you remove the sphere from the previous Boolean operation, nothing happen.
This change of behavior makes easier to you to create helper shapes and remove them, without being afraid that the result may impact your final shape.
Anyway, this will not make possible all combinations, because some operations have side effects: if you do an extrude on a rectangle, and you will delete the extrude, the rectangle referenced by your rectangle is hidden, so when the delete logic will hide extrude, both extrude and rectangle are unreachable, and both will be removed from scene.
Probably in future shapes can register with custom delete code, to restore the side effects, if you don't want to do an Undo, but this need some changes in architecture and will make an overhead for someone implementing a new tool to add this extra code, so things may be thought in advance.