Sorry, no deletion here, as was answered on their forum: it will leave holes in the database (LOL?). You may request to deactivate your account at http://osu.ppy.sh/forum/5
URLS:
http://osu.ppy.sh/
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.