How to get rid of someone's old user account?

Brink said:

It sounds like you may have Windows set to automatically sign in to an account at startup, but if the account no longer exists, you may be seeing what you are now.

As a test, use the tutorial below to make sure that you have checked the Users must enter a user name and password to use this computer box to see if it still happens afterwards.

Sign in User Account Automatically at Windows 10 Startup

noooooooooooo I am really scared to do that because I am afraid it won't let me back in again, like with the other account.

If it really is not harming anything to have that other account there, but not really there would it be ok if I just leave it as it is?

I am really afraid to have it where I have to use a password again to be able to log on because then I might end up no being able to get on at all.

Hey guess what? I decided to go ahead and try that and I checked the thing that says users have to sign in with a password, and you were right, there is no longer any third users account! Thank you for that :)

I hope that has also solved the problem of my computer automatically turning itself off every night thing too, but I won't know till tomorrow morning when I wake up...

But anyway now it looks like everything is all cleared up, and THANK YOU for all your help!