In this post, I’ll explain how to delete files known as Flash cookies from a Windows computer using a batch file.

Most people are familiar with the concept of cookies – small files saved to your computer by the web sites you visit – and how to delete them. But there is a wide-spread misconception that simply deleting your cookies erases your tracks. Even when you’ve instructed your browser to delete cookies and browsing history, a potentially large collection of files remains, and the paths to these files contain the domain names of the sites that have placed them on your computer.

Local Shared Objects (LSO), commonly called Flash cookies, are collections of cookie-like data stored as a file on a user’s computer. LSOs are used by all versions of Adobe Flash Player…

With the default settings, Adobe Flash Player does not seek the user’s permission to store LSO files on the hard disk.

There is relatively little public awareness of LSOs, and they can usually not be deleted by the cookie privacy controls in a web browser.

http://en.wikipedia.org/wiki/Local_Shared_Object

The files are saved to two locations in the roaming profile:
%APPDATA%\Macromedia\Flash Player\#SharedObjects
and
%APPDATA%\Macromedia\Flash Player\macromedia.com\support\flashplayer\sys

As an example, a visit to YouTube will result in the following folders being created:
C:\Users\Oliver\AppData\Roaming\Macromedia\Flash Player\#SharedObjects\KV9EDJYY\s.ytimg.com
C:\Users\Oliver\AppData\Roaming\Macromedia\Flash Player\macromedia.com\support\flashplayer\sys\#s.ytimg.com

Create a text file with the following lines, then save it as deleteLSOs.bat. Run the batch file to delete and remake these folders, thereby clearing all of the subfolders and files.

@echo off
copy "%APPDATA%\Macromedia\Flash Player\macromedia.com\support\flashplayer\sys\settings.sol" "%USERPROFILE%\Local Settings\Temp\settings.sol"
rmdir /s /q "%APPDATA%\Macromedia\Flash Player\#SharedObjects"
md "%APPDATA%\Macromedia\Flash Player\#SharedObjects"
rmdir /s /q "%APPDATA%\Macromedia\Flash Player\macromedia.com\support\flashplayer\sys"
md "%APPDATA%\Macromedia\Flash Player\macromedia.com\support\flashplayer\sys"
copy "%USERPROFILE%\Local Settings\Temp\settings.sol" "%APPDATA%\Macromedia\Flash Player\macromedia.com\support\flashplayer\sys\settings.sol"

Note that the script backs up and then restores a settings.sol file that contains the Flash Player global settings, which can be managed from the Flash Player Settings Manager.