<script type="text/javascript">
            $(function(){
                if(!_spPageContextInfo.isSiteAdmin){ //if user is not side admin then hide the controls

// here you can hide these control using below code not directly using css in cewp

//$("#globalNavBox").css({"display": "none"}); //if you have jquery loaded

    // if you dont want to use jquery then use below code to apply css to your div element

document.getElementById("#welcomeMenuBox").style.display = 'none';
document.getElementById("#globalNavBox").style.display = 'none';
document.getElementById("#suiteBarLeft").style.display = 'none';
document.getElementById("#titleAreaBox").style.display = 'none';
document.getElementById("#ms-help").style.display = 'none';
document.getElementById("#RibbonContainer-TabRowRight").style.display = 'none';
document.getElementById(".ms-cui-tts").style.display = 'none';
document.getElementById(".ms-breadcrumb-top").style.display = 'none';
document.getElementById(".ms-dialogHidden").style.display = 'none';
document.getElementById(".ms-cui-topBar2").style.display = 'none';
document.getElementById(".ms-cui-tts").style.display = 'none';

                }
            });
        </script>