jQuery Grid Plugin - jqGrid

I may as well be new to jqGrid, since this is the first time I've used it in 2 years! Anyway, I am attempting to construct a grid with a delete icon in the first column of each row, no editing is allowed, just delete. In the examples under predefined formatter I saw a grid similar to what I want to do, except that it also allowed editing. I get it to paint correctly, but I really do not understand what I need to do to make the delete operation actually do the right thing. When I watch what goes on in firebug, I see it fires off an http request to ajax.php with no parameters. I guess I am somehow supposed to provide that, but I really do not know how to do it. At minimum, I would like to provide an operation (delete) and a row id, so I can have the server code take care of the deletion. Anyway, what follows is the code. If someone could enlighten me, I would appreciate it.

jQuery(document).ready(function() {
     jQuery("#list1").jqGrid({
         url:'ajax.php',
         datatype:"xml",
         colNames:[' ', 'Keyword','Competition','Searches','CPC'],
         colModel:[
             {name:'myac', width:25, fixed: true, sortable:false,resize:false,formatter:'actions',formatoptions:{editbutton:false,delbutton:true}},
             {name:'keyword',index:'keyword', width:300},
             {name:'competition',index:'competition', width:80, align:'right'},
             {name:'searches',index:'searches', width:70, align:'right'},
             {name:'cpc',index:'cpc', width:40, align:'right'}
         ],
         rowNum:10,
         autowidth:false,
         rowList:[10,20,30],
         pager:jQuery('#pager1'),
         sortname:'id',
         sortorder:"desc",
         caption:"XML Example",
         editurl: 'ajax.php'
     }).navGrid('#pager1',{edit:false,add:false,del:false});
 });