At startup, OS tries to log into nonexistent (?) user account

I bought a refurbished Laptop that came with a pre-installed Windows 10. The seller is a store I consider trustworthy.

At the very first startup after receiving the laptop, it booted straight to desktop into a user profile called "Nutzer" (1), no password prompt.

As my name happens to not be "Nutzer", neither is my SO's, I decided to create two new local administrator profiles with our names, logged into one of them and deleted "Nutzer". I did all this on the Settings / Accounts / Other Users page from Windows 10.

However, whenever I restart the machine now, it first tries to log into "Nutzer" profile and it gives me a "Wrong username or password, please try again" - message. I then have to manually select one of our actual profiles in the bottom left corner to log in properly.

This site gave some tipps on how to completely remove users from W10, but they did not help:

• In Windows' Computer Management, I checked Local Users and Groups, there are six users altogether: The two accounts I created, "Administrator", "DefaultAccount", "Guest" and "WDAGUtilityAccount".
• I checked regedit, the two ProfileList entries with long identifiers only have myself and my SO respectively as ProfileImagePath key.

How do I completely remove any references to this "Nutzer" user? How do I change W10's behaviour so that it does not try to log into that account as default?

Laptop is a 2018 Lenovo Thinkpad X380 Yoga, if this matters.

(1) "user" in english, however german Windows uses the word "Benutzer" to distinguish profiles, so I believe this is something set up by the laptop vendor

Solution 1:

If the login screen tries to automatically fill in a password, this might be the "automatic logon" option:

• Open HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon in Regedit.
• Delete the 'values' DefaultUserName, DefaultPassword, DefaultDomainName, and AutoAdminLogon.

(Also run control userpasswords2 and make sure "Users must enter a user name [...]" is checked.)

Solution 2:

This was going to be a comment, but really should be an answer…

You consider the store 'trustworthy'… though not necessarily 'smart'.
When you get a machine, new or second hand, it ought to be scrubbed cleaner than clean & ready for you to start to enter your first account login details, like from scratch. I'd either nuke & pave it entirely or take it back for them to do it.
That's one dumb business practise they're employing. You should not need to be doing any of this, nor do you know what else they may have put on the machine.