Created Retired tag, hide sold-out products, except on Retired category page.

squarespace-hide-sold-out.js

window.onload = function () {
    var divsToHide = document.getElementsByClassName("ProductList-item sold-out");
    for(var i = 0; i < divsToHide.length; i++){
        if(window.location.href.indexOf("Retired") > -1) {
            return;
        }
        divsToHide[i].style.visibility = "hidden";
        divsToHide[i].style.display = "none";
    }

    var divsToHideWrapper = document.getElementsByClassName("ProductList-grid clear");
    for (var x = 0; x < divsToHideWrapper.length; x++) {
        divsToHideWrapper[x].style.display = "flex";
        divsToHideWrapper[x].style.flexWrap = "wrap";
    }
}

Updated with flexbox to fix the 'float' + :nth-child(3n+1) + :nth-child(2n+1) css the default theme uses.