We could not find options for quick account deletion. However, from their ToS it should be clear you need to contact them and request deletion. Obviously, if you find it necessary, anonymisation is an option too. See here:
You may update your Personally Identifiable Information by logging into the Site and visiting your user account page. You may also contact us via firstname.lastname@example.org. We try to answer every email promptly, but may not always be able to do so. Keep in mind, however, that there will be residual information that will remain within our databases, access logs and other records, which may or may not contain your Personally Identifiable Information.
If you signed up for Coursera using a third-party login such as Facebook or Twitter, you probably want to revoke all access from Coursera. Click the icon below to find out how.