try like this
<!DOCTYPE html>
<html>
<body>
<p>An unordered list:</p>
<ul>
<li>Coffee</li>
<li>Tea</li>
<li>Milk</li>
</ul>
<input id="myCheck" type="checkbox" value="0" />
<p id="Naveen">
<select>
<option value="volvo">Volvo</option>
<option value="saab">Saab</option>
<option value="mercedes">Mercedes</option>
<option value="audi">Audi</option>
</select>
<select>
<option value="volvo1">Volvo1</option>
<option value="saab1">Saab1</option>
<option value="mercedes1">Mercedes1</option>
<option value="audi1">Audi1</option>
</select>
<select>
<option value="volvo2">Volvo2</option>
<option value="saab2">Saab2</option>
<option value="mercedes2">Mercedes2</option>
<option value="audi2">Audi2</option>
</select>
</p>
<button onclick="myFunction()">Try it</button>
<p id="demo"></p>
<script>
function myFunction() {
var xc = document.getElementById("myCheck").checked
alert(xc);
if(xc==true){
var x = document.getElementsByTagName("LI");
for (var i=0, max=x.length; i <=max; i++) {
alert("hi");
document.getElementById("Naveen").style.display='none'
}}
}
</script>
</body>
</html>