To update values in a custom field range
From here you can
You will need to do this for each valid value in the range, as the other values do not automatically re-order themselves.
Bulk actions available depend on your user access.
For example if your privilege does not allow you to delete items, or allows you to only delete articles that you have created, then there is no 'Delete' action in the list of options. If your privilege does not allow you to update items, or allows you to only update items you have created, then this menu will not be available for you at all.