You can do it, for sure. I did it within three days of setting mine up because of the immediate spam I received. I went with a blogger account instead which for sure has its own issues but at least is spam free.
To delete your account, log in to your account and click the Account Settings link next to your photo on your profile page. You will arrive at the Change Account Settings page. Right below the page title you will see three tiny links. Two of them, View My Profile and Edit My Profile are in red. The third link - Cancel Account is in gray, so it is not easily noticeable (of course!) The link forwards you to the page titled Cancel MySpace Account. Pretty easy to figure out from there.