Info straight from myspace
How do I delete my account?
If you wish to permanently terminate your MySpace account, start by clicking "Home" in the top navigation menu from any MySpace web page. From your personal home page, click the "Account Settings" next to your default picture. From your "Change Account Settings" page, click the "Cancel Account" link, found just above the "My Account Settings". On the "Cancel My Account" page, click the "Cancel My Account" button. Check the email account that you used to create your account. Follow the instructions in that email to delete your account. Keep in mind, cancelling your MySpace account will PERMANENTLY REMOVE all of your profile information from MySpace, including your photographs, comments, blogs, and your personal network of friends. This information cannot be restored. You may re-register with your current email address after canceling, but you will need to rebuild your personal network from scratch.
Just copied and pasted from myspace
Or log in and go and click on the "help" tab at the top right of my home page.
Infos there.
Ark