el.style.zoom = "";

document.styleSheets[0].cssRules[0].style.removeProperty("zoom");

div.style.removeProperty('zoom');

ELEMENT.className

ELEMENT.className += " " + Name_Of_The_Class

var ClassRegEx = new RegExp('(\s|^)'+Name_Of_The_Class+'(\s|$)');
if (ELEMENT.className.match(ClassRegEx)) {
  ELEMENT.className=ele.className.replace(ClassRegEx,' ');
}

<a href="test.html" style="color:white;zoom:1.2" id="MyLink"></a>

    var txt = "";
    txt = getStyle(InterTabLink);
    setStyle(InterTabLink, txt.replace("zoom:1.2;","");

    function setStyle(element, styleText){
        if(element.style.setAttribute)
            element.style.setAttribute("cssText", styleText );
        else
            element.setAttribute("style", styleText );
    }

    /* getStyle function */
    function getStyle(element){
        var styleText = element.getAttribute('style');
        if(styleText == null)
            return "";
        if (typeof styleText == 'string') // !IE
            return styleText;
        else  // IE
            return styleText.cssText;
    }