how to keep code running after last function executed, im a newbie to this sorry if doesnt make sense

<!DOCTYPE html>
<html>

<head>
    <meta charset="utf-8">
    <title>  Assignment 3 </title>
    <script src="../JAVASCRIPT/question2.js" defer></script>

</head>

<body>

<h1>Shopping List</h1>
<input type="text" id="firstname" >
<input type='submit' onclick='changeText2()' value='Add Item' />
<input type="text" id="delitem" >
<input type='button' onclick='getNames()' value='Delete Item' />
<br><ol id="demo"></ol>

<input type='button' onclick='delevrytin()' id="evetang" value='Delete all' />
</body>

</html>

var list = document.getElementById('demo'); //demo is the organised list 

//this function is for the add button 
function changeText2() {

    var firstname = document.getElementById("firstname").value
    // the if satatement alerts if input is blank
    if ((firstname == "") || (firstname == null)) {

    alert("can't be blank");

    return; //alerts if noting is inputed and add is clicked
    }
    //creates a list item
    var entry = document.createElement('li'); 
    entry.appendChild(document.createTextNode(firstname));
    list.appendChild(entry);
    document.getElementById('firstname').value = ''; //clears textbox
}

// this function clears specific item starting from 0
var list = document.getElementById('demo');
function getNames()
{
    var remov = document.getElementById('delitem').value;   

    list.removeChild(list.childNodes[remov]);
}

//delete all button
function delevrytin()
{
        document.getElementById('demo').remove; 

}

my problem is the delevrytin function when clicked it works but stops the other functions from working. Can anyone solve my problem emphasized text would be greatly appreciated

Solution

all good its running for me now few variables and id's changed

        var list = document.getElementById('org'); // var for the organized list gets it by id

        //this function is for the add button 
        function changeText2() {
            var firstitem = document.getElementById("firstitem").value
            // the if statement alerts if input is blank
            if ((firstitem == "") || (firstitem == null)) {
                alert("can't be blank");
                return; //alerts if noting is inputed and add is clicked
            }
            //creates a list item
            var entry = document.createElement('li'); 
            entry.appendChild(document.createTextNode(firstitem));
            list.appendChild(entry);
            document.getElementById('firstitem').value = ''; //clears textbox
        }


        // this function clears specific item starting from 0
        function getNames()
        {   // creates a variable and assigns it to the  delitem input
            var remov = document.getElementById('delitem').value;   
            //remove - 1 lets you delete the list item but the number beside it
            list.removeChild(list.childNodes[remov = remov - 1]);
        }

        //delete all button
        function delevrytin()
        {       //if there is a child node remove it 
                while (list.firstChild) {
                    list.removeChild(list.firstChild);
                }
        }