The short answer is - you can't.

There are 2 aspects to your problem: the keyring password and the user
(login) password.

When keyring first appears asking for a password to be set you can just
click on OK with the field blank. It will complain about the security risk
but still let you use it. After that always click on "always allow" when it
asks if some app should be allowed to access keyring. It wont ask again for
that app. If you can find the keyring app it gives you the option of
changing this password and you should be able to delete anything there and
save it as a blank password.

As for the user or login password, I don't believe you can install Ubuntu
without entering one. However, there is an option to log in automatically
in the installation. If you missed that you can enable it somewhere in the
system settings. I'm a Kubuntu user so apart from the fact that you must
have it I can't help you find it. You will still need that password to
install anything or do updates. No way around that as far as I know.

If you Google "Ubuntu keyring" and similar phrases you will find a lot of
help and 99% of the answers you need. I've got a couple of books on Linux
but most of what I know came from searches... a word to the wise.