Question

owls eat small vertebrates, including mice and birds. there are some parts of an owls food, including bones and fur, which the owl cannot digest.
many owls regurgitate, or spit up, some of the waste left over from their food. this regurgitated waste is called a pellet. this photograph shows bones inside an owls waste pellet.
which system removes waste that contains fur and bones from the owls prey?
the digestive system the excretory system

Explanation:

The digestive system processes food. In owls, after digestion, indigestible parts like bones and fur are formed into pellets. The digestive system is responsible for handling and eliminating this waste (the pellet). The excretory system mainly deals with liquid waste (like urine - related substances in some animals, but owls' pellet - related waste is from digestion).

Answer:

the digestive system