How do I destroy an image behind another image

How do I destroy an image object which is behind another image object and without using

the name of this image object ?

For example, I have an image of a RifleSight object and behind it I have an image of a victim.

When I touch the Fire button I want the image of the victim to be destroyed but without referring the name

of the victim image (since the victim image may change dynamically).

Is there a way to refer somehow to the layer behind the RifleSight object or maybe the Z position ?

Thanks in advance.

How about putting all of the victims in a family?

Wowww thank you, it was very quick, works like a charm