Play flash intro only once per _Domain_ visit

Can any one point me to a tutorial that shows how to do what the title above says (OR how do delete sharedObject files on user’s computers) using sharedObjects or javascript?

I want the user to be able to see the intro only once, but if he closes the browser or leaves the domain, then I want it to replay. But if he is browsing through pages within the domain, I want the intro not to play again until he leaves domain or closes browser.

I’ve succeeded in getting the sharedObject to be stored so it only plays once, but I don’t know how to make it delete that object on leaving domain or closing out web browser so I can see it again when I revisit the domain.

I also see some stuff on the web about deleting SO’s but it doesn’t say what action invokes the deletion, where do I put the code in my Swf, etc…