linux. How to change the main user?

Question

linux

I need to rename the main user, but I can't do it because it is the main one and the system hangs on it, and I cannot kill all the processes that hang on it, so I need to make sure that another default user is loaded when the system starts. I already did it somehow, but I can’t remember how, and I can’t google it. Thank you.

Answer 1

At system startup, no default user is loaded.
This happens when you start the DE (more precisely, in the DM), and the steps to change depend on which one you have.
For example, I have an autologin user in /etc/lightdm/lightdm.conf

Answer 2

first you need to understand what the main user is ... is it root by any chance?

Answer 3

When the system is restarted, all processes are killed, name the main user)

Answer 4

What kind of nonsense? What nafig the main user? Linux has one permanent user - root. You can easily rename it directly to /etc/shadow and /etc/passwd - because linux doesn't care about the name, its UID is of interest.
But we must start with a task. What for?