Removing textfield completely in subform

Hi,

I want to remove the whole field/attritbute of that particular part of my subform on this form without removing it original form as it can be used for other part, so why my subform become like this? Not just the textfield but including the label I want it to be removed.

here are my codes that i used on Custom HTML below subform

<script>
$(function(){
var field = FormUtil.getField("id_mobile_number");
$(field).attr("disabled", "disabled");
var field = FormUtil.getField("id_position");
$(field).remove();
var field = FormUtil.getField("id_explanation");
$(field).remove();
});
</script>

I've try using this method but doesn't work either

$(id_explanation).remove(); // or
var field = FormUtil.getField("id_explanation");
$(field).hide(); // or
$(id_explanation).hide();