html5 buttons export doesn't exclude the Header Colums

i have a dynamic dataTable function to do a export with

exportOptions: {
    columns: 'th:not(.noexportar)',
    format: {
        body: function (data, row, column, node) {
            data = jQuery('<p>' + data + '</p>').text();
            return jQuery.isNumeric(data.replace(',', '.')) ? data.replace(',', '.') : data;
        }
    }
},

But the Excel file keep the Header Column:

(POS) is the column that i dont wanna show in exports

How i can solve it?