Why does the computer ask me to hold alt and control then press delete to get to

The next part of the question is. If I am hacking an old computer that I do not have a password for. The computer is a Dell E520 running Xp professional.
It asks for: #1 user name I would like to enter a new one.
#2 password That I do not know also want to reset.
#3 domain

I have entered a new administrators name in the Dell bios and given the computer a new password also in the Dell bios

But, I cant get to the start menu.

I tryed microsoft but it is not there policy to violate user passwords