The hour when your facility manager is in the office is called office/working hours. They are there to provide customer service to you and also provide answers to any of your questions, sell supplies you may need to you, receive payments, and so on.
Access hours are simply the main hours in which you can visit your storage unit. Each facility determines these hours. Some self-storage centers offer unlimited accessibility, while others are limited. Some companies grant you access hours from 6 am to 10 pm every day.