"Edit Metadata Fields" option does not allow clearing out already selected fields
When a data package is added to the data cart and user chooses to edit the
metadata fields that get displayed in the downloaded .csv file, a user
does not have an option to discard all or a few of the fields already selected.
In fact, once a few fields are selected and the "save selection" option is
selected, the user has to select at least one field in order to change the
selection any further.