.uploadifyCancel()

$('#someID').uploadifyCancel(ID);

The .uploadifyCancel() method removes a file from the upload queue.  If the file is currently uploading, the upload is canceled and the file is removed from the queue.  When this method is called, the uploadifyCancel event fires and the onCancel function is fired.

Arguments

ID (Required)
The unique ID of the file you want to cancel.  This ID is generated by the Uploadify script when a file is selected and added to the queue.

Demo

Javascript Code
  1. $('#file_upload').uploadify({
  2.   'uploader'    : '/uploadify/uploadify.swf',
  3.   'script'      : '/uploadify/uploadify.php',
  4.   'cancelImg'   : '/uploadify/cancel.png',
  5.   'folder'      : '/uploads',
  6.   'multi'       : true
  7. });
HTML Code
  1. <input type="file" id="file_upload" name="file_upload" />
  2. <a href="javascript:$('#file_upload').uploadifyUpload();">Upload Files</a> | <a href="javascript:$('#file_upload').uploadifyCancel($('.uploadifyQueueItem').first().attr('id').replace('file_upload',''))">Cancel First File</a>