can i see all icloud user names

Thanks for reaching out, Murfis.

It sounds like you're looking to obtain a list of previously used Apple IDs. While this is something that Apple does not provide, we can help give you some suggestions on how to find any Apple ID usernames that you personally registered previously.

Your best bet would be to search your commonly used emails for any reference to the keywords "Apple ID". This should let you see any correspondence that you may have received when using a different account.

There is no way to see any information about Apple IDs you didn't create, however.

Hope that helps!