- Use 'del' instead of 'list.remove()' in
        Catalog.delColumn(). There can be only one column with the
        same name, and it could potentially break catalog metadata as
        remove() may remove more than one element from the list if
        they have the same value. Also, we already have the list index
        we are interested in deleting so it doesn't make sense to look
        up the value and call 'list.remove()' on it.