Final answer:
The decision for a caterer to remove unserved alcohol depends on the service agreement, local laws, and event policies; it's important for caterers to communicate clearly with clients about handling of unserved items.
Step-by-step explanation:
Whether a caterer should always remove any unserved alcohol when leaving a catered event depends on the terms of the service agreement, local laws, and the event's specific policies. If the alcohol was provided by the caterer, it is common for the caterer to retain ownership and remove it at the end of the event. However, if the alcohol is supplied by the host or a third party, arrangements should be made in advance to determine who retains the leftovers. Local laws could also influence this decision, as some jurisdictions have strict regulations on the transportation and disposal of alcohol. Lastly, it's important for caterers to operate ethically and professionally, and clearly communicate with clients about the handling of unserved items, including alcohol, to avoid any misunderstandings.