The FAQ is not completely clear about deletion, neither could we find rock-hard facts about it on their forums. It seems there are 2 possibilities:
1. Send an e-mail, from your customer (Adobe ID) e-mail address, to firstname.lastname@example.org, with your details: name, Adobe ID and request.
2. Alternatively, according to an Adobe page you can give them a ring (in the USA, that is): http://learn.adobe.com/wiki/display/wel/Delete+your+account
If you signed up for Adobe using a third-party login such as Facebook or Twitter, you probably want to revoke all access from Adobe. Click the icon below to find out how.