ТС молчит... И таки да - rowIndex
<style>
button { display:none; }
tbody tr:hover>td>button {display:inline-block;}
tbody tr:hover {
background: #f3bd48;
color: #fff;
}
</style>
<table id='tbl'>
<tbody>
<tr>
<td>11</td>
<td>12</td>
<td>13</td>
<td><button >Del</button></td>
</tr>
<tr>
<td>21</td>
<td>22</td>
<td>23</td>
<td><button >Del</button></td>
</tr>
<tr>
<td>31</td>
<td>32</td>
<td>33</td>
<td><button >Del</button></td>
</tr>
</tbody>
</table>
<script>
[].forEach.call(document.querySelectorAll('button'), function(but) {
but.onclick = function() {
var tr= this.parentNode.parentNode;
tbl.deleteRow(tr.rowIndex);
}
});
</script>