Hide "Group" Header and ':(colon)' using css and Javascript in SharePoint list

Add  below code to either specific view of the list or  to script editor web part

.ms-gb a

{

display:none !important

}

</style>

<script type="text/javascript">

    _spBodyOnLoadFunctionNames.push("HideHeaders");

    function HideHeaders() {

        var elements = getElementsByClassName(document, "td", "ms-gb");

        var elem;

        for (var i = 0; i < elements.length; i++) {

            elem = elements[i];

            elem.childNodes[1].nodeValue = elem.childNodes[1].nodeValue.replace(':', '');

        }

        elements = getElementsByClassName(document, "td", "ms-gb2");

        for (var i = 0; i < elements.length; i++) {

            elem = elements[i];

            elem.childNodes[2].nodeValue = elem.childNodes[2].nodeValue.replace(':', '');

        }

    }

    function getElementsByClassName(oElm, strTagName, strClassName) {

        var arrElements = (strTagName == "*" && oElm.all) ? oElm.all : oElm.getElementsByTagName(strTagName);

        var arrReturnElements = new Array();

        strClassName = strClassName.replace(/\-/g, "\\-");

        var oRegExp = new RegExp("(^|\\s)" + strClassName + "(\\s|$)");

        var oElement;

        for (var i = 0; i < arrElements.length; i++) {

            oElement = arrElements[i];

            if (oRegExp.test(oElement.className)) {

                arrReturnElements.push(oElement);

            }

        }

        return (arrReturnElements)

    }