User login after boot

Running Win 10 Pro, 1909 level. This is a new PC and after getting all the kinks worked out, I'm left with one irritating thing. I have just one user ID on this system, and that's me, set up as the administrator. When I boot the system, in the lower left corner of the screen, there are two possible user IDs to select. They are both me - the info displayed is identical. If I try to log on using the ID presented in the middle of the screen, it rejects the log on because the password is not correct. If I then select the first user ID in the left corner of the screen and enter the same password that failed with the other ID, the log on completes just fine. I'd really like the second "phantom" ID to go away. Any ideas as to why that second ID occurrence is there, and can I delete it somehow? Thanks.

Press Win + R keys to bring up run dialog box. Run:
netplwiz

Uncheck the box for "Users must enter a user name and password to use this computer"
Click Apply.
In the next screen that appears click OK. (Leave the password fields blank).
Put the check back in the box for "Users must enter a user name and password to use this computer"
Click OK.

To dalchina: Thank you for your response. I guess I didn't go a good job of describing the problem, and I will repeat what I said in my post: "I have just one user ID on this system, and that's me, set up as the administrator." I am fully aware of how to view the users of the system and how to delete and add users. The problem here is: there is only one user shown for the system. But, when I try to log in after a reboot, there are two occurrences of that user ID presented in the lower left corner of the screen. The one that is automatically selected (the bottom of the two) will not accept my pin or password. When I manually select the upper of the two presented, the password is accepted and all is well. I did considerable research (really good with a search engine) before posting my question here.

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NavyLCDR said:

Press Win + R keys to bring up run dialog box. Run:
netplwiz

Uncheck the box for "Users must enter a user name and password to use this computer"
Click Apply.
In the next screen that appears click OK. (Leave the password fields blank).
Put the check back in the box for "Users must enter a user name and password to use this computer"
Click OK.

OK - here's what happened when I did that: To begin with, the check box was NOT already checked. There were two users listed for the system: me as administrator and Guest as guests. So, in the spirit of trying anything, I checked the box and then restarted the PC. This time, the dual user IDs were not present in the lower left corner, and the system accepted my password just fine. Maybe this makes sense to you, but not to me. Not going to argue with success, but how it behaves is not logical to me. Now, I'd really like to change the user name, but have not found a way to do that. I suppose I could add another user with the name I want and give that user admin authority, and then use that ID to log in and delete the original ID. Sounds reasonable, but what could possibly go wrong !?