To amend your availability for a particular location:
Go to your Calendar
Click on the day you wish to edit
Select the locations you wish to update your opening hours for
Select all the dates you wish to edit your opening hours for
Select the times that you wish to set yourself as available for. When the time is displayed in purple, indicates it has been selected
Press save
Note - This will override the default opening hours that has been added to your location for the dates selected
To edit your default opening hours, see article: How do I set my default availability for a location?