Delete your Ubuntu One Account
Ways to delete this Account:
Delete this account by writing a mail
Yes and no, it depends on which type(s) of accounts, and you will need to delete the accounts in the correct order. All accounts are tied to Ubuntu One's Single Sign-On (login.ubuntu.com), so that is the account you should close last. Everything else, such as Launchpad.net, cloud file storage, AskUbuntu, and other accounts should be closed first if possible. This is especially important if you have any paid services attached, to make sure you won't be billed for anything after closing the accounts. The last step is to delete your Single Sign-On (SSO) account. SSO accounts must be deleted manually by the Ubuntu One staff.