To close your account, please login and visit https://unsplash.com/account/close.
Please note: Closing your account deletes all of your images and all associated data, it also removes your usernames availability permanently.
If you're just looking to delete one (or all) of your images, you can do that from the manage photos page.
If you're looking to manage the the emails you receive, or unsubscribe to them completely - but want to keep your account, you can do that from the email settings page.