You cannot delete your account yourself. However, the admins are nice and can delete your account.
Contact them with a request to delete your account. Briefly include a reason why you wish to do so. Account removal will be done within 24 hours.
For a bit more info, see this: http://www.songwritingfever.com/forum/how-can-delete-my-account-3-385.html
URLS:
http://www.songwritingfever.com