My project appeared to be have a heavy download size so I experimented with deleting images and cut it down to the bare minimum but it was still high. I then found that although I had deleted sprite objects from the layouts they were still held in the project object list and had to be deleted from there as well.
I don't understand your point.
This is covered in the Manual:
Deleting from the Layout View will not remove an object from the project completely. The only way to fully remove an entire object type from the project is to delete it from the Project Bar.