jpk: remember that Windows 10 provides TWO different types of userids:
- A "local account" (which, prior to Win 8 is the only type of account available). A local account may or may not have a password (just like in Win 7)
- A "Microsoft Account", which MUST have a password.
Sounds like you originally had a local account, but later switched it to a MS Account and when you did that, you could no longer sign in without a password. Therefore, the suggestion from davehc about using "netplwiz.exe" isn't going to help as it's only applicable for local accounts.
There are a lot of pros and cons as to which type of account is best for you. Take a minute to review an
article that discusses this.
For my residential customers, I usually setup local accounts. For corporate customers, it can go either way depending on their requirements.
Hope this helps.