To solve this issue, stop the event bubbling when clicking the linkbutton
onclick=\"OPT_SYSTEMUSER_REMOVE('"
+ row.objectID + "');event.stopPropagation?event.stopPropagation():window.event.cancelBubble=true;\"
or delay the delete action
OPT_SYSTEMUSER_REMOVE = function( _objectID ){
$('#dg').datagrid('selectRecord',_objectID);
var row = $('#dg').datagrid('getSelected');
var index = $('#dg').datagrid('getRowIndex',row);
$('#dg').datagrid('unselectRow',index);
setTimeout(function(){
$('#dg').datagrid('deleteRow',index);
},0);
};