It's still a bit complicated, but it seems that you can now delete your account this way:
Log in to your Evernote account at Evernote Web
Click on "Settings" in the top right corner.
Click on "Personal settings" on the left-hand side.
Replace the current email with "closed_(youremailaddress)"
Click on "Update" below.
Note: You will be prompted to type your password again.
Once you have completed this step, return to your Notes list, select all notes and delete them, then select the Trash and Empty the Trash.
Then, please go to: https://www.evernote.com/Deactivate.action
Not a true deletion, but let's make it a grey entry.
If you signed up for Evernote using a third-party login such as Facebook or Twitter, you probably want to revoke all access from Evernote. Click the icon below to find out how.