From their FAQ (http://www.wuala.com/en/support/faq/c/5):
How do I delete my account?
Please write us an email [[email protected]]. It is important to state your username and send the email from the email address you specified in Wuala.
URLS:
http://wuala.com
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.