Are you a DreamHost customer, or are you talking about Dreambook?
In either event, you can cancel a hosting account by contacting support through the web admin panel, or from your account contact address.
Dreambook is a free service; you can get Dreambook support by contacting helpdreambookcom.
Generally, we'll "close" accounts, but we don't delete them from our system entirely. You can end all of your services and remove all payment information from your account, but if you contact support, they can do it for you as well. I would suggest contacting support about your concerns.