When I was little I thought you needed an account for each computer. I was silly back then. :P Can you delete the accounts superpokemon and Sinnoh Champion? They use email addresses I need to use because the one I have is messed up. Plus I forgot the passwords to them, so they're worthless.
User accounts can only be deleted if they do not have any posts. If you have old accounts they are not hurting by existing.
I changed the email addresses on them so that you can use the email for your current account if you need to.
Just dont use them and it will be fine, if you cant log into them then its not a problem.