Many web users today are aware of browser cookies, and every major browser allows users to view and delete the browser cookies stored on their computer. However, many websites use different types of local storage as well, including Adobe Flash Player Local Shared Objects (LSOs), a.ka. "Flash cookies."
In the past, to delete Flash LSOs, you had to visit an online settings application on Adobe's website. Now, with Adobe and others in the web community, Google designed the NPAPI ClearSiteData API, which Adobe has implemented in Flash Player 10.3, has made it possible to delete Flash LSOs directly from the browser itself.
As of this week's Chrome Dev channel release, you can delete local plug-in storage data (such as Flash LSOs) from within Chrome by clicking Wrench > Tools > Clear browsing data and selecting "Delete cookies and other site and plug-in data."
"Plug-in data" here refers to client-side data stored by plug-ins that obey the NPAPI ClearSiteData API, such as Flash Player 10.3. You can also configure Chrome's content settings to clear plug-in data automatically whenever you close the browser.
[Source: Chromium blog]