Windows 10 Opens to Phantom Account, After 20 Secs Shows 2 Accts

Dell 35xx machine with 8GB RAM was running Win 8.1.
We used a MS disk download to force upgrade to Win 10 on this machine to match others in the organization.
The user (call this person Adam) of the 35xx machine left the group.
We moved the machine to a new person (Zena), who was set up with a user account at the time of upgrade to Win 10.
Now, the machine boots up fine but tries to sign on to the Adam account and displaying an error for an incorrect password.
We do not have a USB or disk to reset the Adam password.
If we click OK on the Adam "Try Again", both the Adam and the Zena account choices show up at the bottom left of the screen. Then, we can log in Zena with no problem.
Note: If see the Adam "Incorrect Password" message, and wait 20 seconds the screen goes to the "beach cave"; when we click to log in from there - only the Zena "Enter Password" shows up.
The Adam directory is easily found on the disk.
Using Control Panel, we cannot see the Adam User account - only Zena (who is set as an administrator).
So the Adam directory can be seen but not deleted, and it also is the directory for the Office 365 subscription (so Adam is the default for Windows 10 and for Office 365).
We would like to eliminate Adam and clean up by having Zena for both - but the most annoying is the log in defaulting to Adam.
How can we delete the Adam account altogether ?
All help will be greatly appreciated. So, thanks in advance.

Brink said:

Hello J2RiseR, and welcome to Ten Forums. :)

It sounds like Windows may have been set to automatically sign in to this "Adam" account at startup.

Checking the Users must enter a user name and password to use this computer box in netplwiz, or setting to automatically sign in to the "Zena" account at startup should sort this for you if this is the case.

Sign in User Account Automatically at Windows 10 Startup

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Brink -
Thank you, very much.
Indeed, your suggestion did sort out the phantom account automatic log in.
When we used the "netplwiz" as you directed, we saw that there were 2 users - Zena and "HomeGroup$".
We checked "must enter user name and password ..." as directed. We also, subsequently, removed the "HomeGroup$" user(s).
Upon Restart, we now are taken to a lock screen, on click to the correct user - Zena.
Thanks again.
Now, on to those extra "Adam" directories and the Office 365 installation there.
Thanks.