Just like inserting and updating deleting is used the same way.
The related example for this is as follow.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>PHP jqGrid Class Example</title> 

<link rel="stylesheet" type="text/css" media="screen" href="themes/redmond/jquery-ui-1.7.1.custom.css" />
<link rel="stylesheet" type="text/css" media="screen" href="themes/ui.jqgrid.css" />

<script src="js/jquery-1.3.2.min.js" type="text/javascript"></script>
<script src="js/i18n/grid.locale-en.js" type="text/javascript"></script>
<script src="js/jquery.jqGrid.min.js" type="text/javascript"></script>
<script type="text/javascript">
jQuery(document).ready(function(){
....
// Craeate the grid manually
jQuery("#grid").jqGrid({
"colModel":[
     {"name":"OrderID","index":"OrderID","label":"ID","width":60, "key":true},
     {"name":"OrderDate","index":"OrderDate", editable:true},
     {"name":"CustomerID","index":"CustomerID", editable:true},
     {"name":"Freight","index":"Freight", editable:true},
     {"name":"ShipName","index":"ShipName", editable:true}
],
"url":"querygrid.php",
"datatype":"json",
"jsonReader":{repeatitems:false},
"pager":"#pager",
// now we should set the url where we post the data
// in this case the same url
"editurl": "querygrid.php",

// tell the grid to post the OrderID as primary key

"prmNames":{"id":"OrderID"}

});
// Set navigator with deleting and search enabled.
jQuery("#grid").jqGrid('navGrid','#pager',{add:false,edit:false,del:true});
......
});
</script>

</head>
<body>
......
<table id="grid"></table>
<div id="pager"></div>
.......
</body>
</html>

As can be seen we change only the options in navigator to support deleting

The related PHP code

<?php
require_once 'jq-config.php';
// include the jqGrid Class
require_once "php/jqGrid.php";
// include the PDO driver class
require_once "php/jqGridPdo.php";
// Connection to the server
$conn = new PDO(DB_DSN,DB_USER,DB_PASSWORD);

// Create the jqGridEdit instance
$grid = new jqGridEdit($conn);

// Write the SQL Query
$grid->SelectCommand = 'SELECT OrderID, OrderDate, CustomerID, Freight, ShipName FROM orders';
$grid->dataType = "json";

// We should determine if we add a record.
// jqGrid send oper to identify the operation performed
// in this case we should check for add

$oper = $_POST['oper'];
if($oper == 'edit') {
   $grid->table = 'orders';
   $grid->setPrimaryKeyId('OrderID');
   $data = $_POST;
   $grid->delete($data);
} else {
   $grid->queryGrid();
}
?>