How to change the username? "root" is default.
And, I want to change it.

Leave root it is the system administrator.

DO NOT try to change it.

DO NOT try to delete it.

Add a new user via the useradd command.

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How to do it?

Please leave this root alone. You are able to add a new user in the way described by @rtmistler, but you would also have to grant privileges to this new user. It's not easy when you must do it with BusyBox.

PS.
4MLinux automatically creates users (and sets their privileges) for server software and some desktop applications (e.g. Chrome).

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Oops!
There is no "useradd" applet in BusyBox. The "adduser" applet must be used instead.

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Thanks!

Reason #237 for "Why I hate Busybox"

OK I'm exaggerating.

Honestly over recent years I've given it some thumbs up because it's seemed to have improved and really followed the system commands way better. Example years ago things like ls, or grep did not adhere to the real system calls and hence if you used them in a script you could not use certain features, sometimes the very features you needed. But that was like 10+ years ago and I've encountered it on systems and found it to be improved.

Good detection zk1234! I'm disappointed that they felt necessary to swap the command name around though.

They didn't just swap the name around. Useradd and adduser do things differently. Adduser is easier to use, since it's interactive and does more and better housekeeping. Useradd isn't used as much these days, AFAICT. I haven't bothered with it in years.

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