Removing every child element EXCEPT first child?

To remove all but the first child:

while (cntnt.childNodes.length > 1) {
    cntnt.removeChild(cntnt.lastChild);
}

You could also filter by the id of the select you want to save

while (cntnt.lastChild.id !== 'pSort') {
    cntnt.removeChild(cntnt.lastChild);
}

Or your could just get the innerHTML of pSort and append it with the ajax response right away, without having to loop to remove elements

cntnt.innerHTML = document.getElementById('pSort').innerHTML + return_data;

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