You can only delete a property if you have the appropriate access rights. If the Delete option on the File menu is disabled, you do not have the appropriate access rights to delete locations.
You cannot delete a location if there are locations below the property in the hierarchy. When you are viewing the Property Tree Browse Window, any locations that have locations or assets below them will have a plus sign next to them.
You cannot delete a location if it is being referenced by any other item in Pinnacle. If there are assets that have the property selected as their location, or MWAs that have been raised for the property, you must remove these references before you can delete the property.