You cannot delete your account.
Try to contact them:
Go to http://www.priceline.com/customerservice/customerservice.do and click the “Contact Us” tab.
Fill out the form, and select “My Profile” from the “Product” list.
Please note that AccountKiller.com is not associated with the business listed on this page. AccountKiller provides easy-to-understand instructions and guides on how to cancel charges and relationships from the list of businesses on our site, we have no affiliation with these businesses.