<form>
    <input type="text" name="First"  value="First Name">
    <input type="text" name="Last"  value="Last Name" >
    <div class="phones">
        <input type="text" name="Telephone"  value="Telephone" ><br>
        <input type="text" name="Telephone"  value="Telephone" >
    </div>
    <br>
    <input type="submit" name="" value="Add">
</form>

var inputs = document.getElementsByTagName('form')[0];

var cloneInp;
function iff() {
    cloneInp = inputs[2].cloneNode(true);
    inputs[2].after(cloneInp)
}

function remov() {
    inputs.removeChild(inputs[0]);
}