Jquery remove text from span

$('span.ms-error:contains("External Data")').hide();

If you know for sure that these span's are inside a certain table or a div then target it specifically inside those to make the script perform better.

eg.

$('.ms-usereditor span.ms-error:contains("External Data")').hide();

var spans = $('.ms-error');

spans.text(''); // clear the text
spans.hide(); // make them display: none
spans.remove(); // remove them from the DOM completely
spans.empty(); // remove all their content