If you'd like to permanently delete your account, you can do so via the website. Here are the instructions:
1. If you have subscribed through the mobile apps, make sure you cancel your subscription before deleting your account. (Here are instructions for that: http://help.eatthismuch.com/knowledge_base/topics/how-do-i-unsubscribe )
2. Click your username in the sidebar.
3. Click "Membership status"
4. Click "Delete your account". Then confirm your request by clicking the checkbox, and it's done!