dropdown option:first' code example
Example 1: select first option in dropdown jquery
myElement.find('option:eq(0)').prop('selected', true);
Example 2: jquery change selected option to first
$('#agregador-de-servicios')[0].selectedIndex = 0;
myElement.find('option:eq(0)').prop('selected', true);
$('#agregador-de-servicios')[0].selectedIndex = 0;