If you are an Evernote premium member, the first step towards getting rid of your Evernote account is by cancelling your subscription. You can do this from the Evernote website, under your account settings. Log into Evernote and move all of your items to the trash. Then, open the Trash folder and select Empty Trash. All of your notes will be permanently deleted and will be irretrievable. This will remove them from the Evernote servers. You can log into your Account Settings page and remove your email address from your account. Evernote will no longer be able to retrieve your account password via email. In the Settings section of your account, you will find a Deactivate Account link. This will disable your account. Any remaining notes will not be deleted, and your account will still be available if you want to log in with your old username and password. You cannot permanently delete your account.

Summary:
Cancel your subscription (if applicable). Delete all of your notes. Remove your email address (optional). Deactivate the account.