인풋 한개 일 때는 삭제가 되지 않게 하는 방법 문의 드립니다

<input style="float:right; margin:5px 2px" type="button" value="상품추가" onclick="ob_adRows.addRow()"/>

<table id="table1" cellspacing="0" cellpadding="0" width=100% >
            <tr class="sound_only">
                <th>구분</th>
            </tr>
            <?php 
                $wr31_cnt = count($wr_31x);
                    if(!$wr31_cnt){
                    $wr31_cnt = 1;
                    }
                for ($i = 0;  $i < $wr31_cnt; $i++) {
            ?>


            <tr>
<td style="padding:10px 0 10px 0;" align="center"> 
<p><input type="text" id="input1" name="wr_31x[]" value="상품명" style="border:hidden;" readonly><input type="text" id="input2" name="wr_32x[]" value="<?=$wr_32x[$i]?>">
<input type="text" id="input1" name="wr_33x[]" value="상품URL" style="border:hidden;" readonly><input type="text" id="input2" name="wr_34x[]" value="<?=$wr_34x[$i]?>"></p>
<br>
<p><input type="text" id="input1" name="wr_35x[]" value="가격" style="border:hidden;" readonly><input type="text" id="input2" name="wr_36x[]" value="<?=$wr_36x[$i]?>">
<input type="text" id="input1" name="wr_37x[]" value="수량" style="border:hidden;" readonly><input type="text" id="input2" name="wr_38x[]" value="<?=$wr_38x[$i]?>"></p>
<br>
<p><input type="text" id="input1" name="wr_39x[]" value="옵션" style="border:hidden;" readonly><input type="text" id="input3" name="wr_40x[]" value="<?=$wr_40x[$i]?>">


               
               
          <input type="button" value="삭제" class="tabledel_btn" onclick="ob_adRows.delRow(this)"/> </p>
                  
                </td>
            </tr>
</div>
            <?php } ?>

<table id="dyntbl1" cellspacing="0" cellpadding="0"></table>
<script>
            function adRowsTable(id){
                var table = document.getElementById(id);
                var me = this;
                    if(document.getElementById(id)){
                        var row1 = table.rows[1].outerHTML;
                        function setIds(){
                        var tbl_id = document.querySelectorAll('#'+ id +' .tbl_id');
                        for(var i=0; i<tbl_id.length; i++) tbl_id[i].innerHTML = i+1;
                    }
                    me.addRow = function(btn){
                    btn ? btn.parentNode.parentNode.insertAdjacentHTML('afterend', row1): table.insertAdjacentHTML('beforeend',row1);
                    setIds();
                    }
                    me.delRow = function(btn){
                    btn.parentNode.parentNode.outerHTML ='';
                    setIds();
                    }
                    }
                }
            var ob_adRows = new adRowsTable('table1');
</script>