How to delete account or change username?

An apparently functioning AIM chat account will not accept name/pw to log into yahoo to change anything?

• It is and OLD account, but my old buddy list autofilled. I'd like to remove some of them, however, and update info for others, but I can find no way to access that info to change anything. I am accessing using Mac OS X Leopard using iChat. Everything is dimmed. If I try to log into yahoo with the username/pw for messenger, it won't accept it. I don't even know how to delete this username/pw if I wanted to... any ideas?

• Answer:

  it's difficult also to delete an account if you don't remember your password or if your password is not acceptable since the deletion page needs your password for confirmation before you can delete that account. you may leave it forever if you don't like and create a new one. *we're still trying to program Mac from Windows so we don't have much knowledge with Mac yet.