app/assets/javascripts/admin/util.js.erb
$(document).ready(function() {
$('a.close').click(function(event){
event.preventDefault();
$(this).parent().slideUp(250);
});
// Spree locates hidden with prev(), which with our current version of jQuery
// does not locate the hidden field, resulting in the delete failing. This
// handler updates the hidden field, fixing the problem.
$('body').on('click', 'a.remove_fields', function() {
$(this).next("input[type=hidden]").val("1");
return false;
});
});