Final answer:
When encountering someone sitting in the lobby of an office building after normal closing time, you should approach the individual and ask if they need assistance or if they are waiting for someone. If they don't require help and are simply waiting, politely ask them to leave, prioritizing the safety and security of the building and its occupants.
Step-by-step explanation:
While performing access control duties at a desk in an office building an hour after normal closing time and seeing someone sitting in the lobby on a bench, there are a few things you can do. First, you should approach the individual and ask if they need any assistance or if they are waiting for someone in particular. If they need help, you can offer assistance as needed. However, if they do not need assistance and are simply waiting, it would be best to inform them that the building is closed and politely ask them to leave. It is important to prioritize the safety and security of the building and its occupants.