Deleting an item (which differs substantially from deleting a layer) erases every trace of an item from the archive, as if that item had never existed or had never been captured. This can be useful for recovering archive space consumed by items—particularly ones that have since been deleted—that you no longer want to preserve.
You can delete a file, folder, volume, or even an owner (discarding all items ever captured using that identity key).
Contrast the effects of deleting an item (shown below) with that of deleting a layer:
Layer shading has no effect on the delete item command.
Deleting an item expunges it from every layer of the archive. In other words, you can't delete an item from some layers, but not others.
Deleting an item may modify many layers in the archive. If the archive is connected to a stack, every layer affected will also have to be replaced in the stack.
More importantly, copying a layer to the stack requires that all later layers affected by the deleted item must be replaced first. This is because of the way layer references work; a newer layer in the stack might refer to the delete item, so it must be replaced before the earlier layer (which no longer contains that item) can be replaced.
In other words, deleting an item from an archive may involve replacing a lot of layers in the stack, and will require that they be replaced in the correct order.