If you locate your Yahoo Sign in page, and go to forgot password/screen name, they will email you what information you forgot and you can then delete it from there.
If you know one or the other, see the answer provided above.
If you get access eventually:
Remove all content and information that you added to Yahoo! 360. Make all your settings (blog, communication, alerts...whatever) private or to "Just Me". Don't return to 360.yahoo.com.
You can't completely get rid of the 360 functionality without deleting your entire Yahoo account (mail, photos, etc.). You can only make sure no one who you haven't invited can view a feature and make sure that there's nothing there to view.
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Verified answer
If you locate your Yahoo Sign in page, and go to forgot password/screen name, they will email you what information you forgot and you can then delete it from there.
If you can't access your account (i.e. don't know your account name or password), then try contacting Customer Care by press that button on this page:
http://help.yahoo.com/l/us/yahoo/edit/registration...
If you know one or the other, see the answer provided above.
If you get access eventually:
Remove all content and information that you added to Yahoo! 360. Make all your settings (blog, communication, alerts...whatever) private or to "Just Me". Don't return to 360.yahoo.com.
You can't completely get rid of the 360 functionality without deleting your entire Yahoo account (mail, photos, etc.). You can only make sure no one who you haven't invited can view a feature and make sure that there's nothing there to view.
Good luck!