How could I do this?

I tried:

1. putting the chromebook in dev mode
2. enabling debugging options
4. browse as guest(also tried with a google account)
5. open shell ctrl + shift + t
6. enter shell and sudo su
7. enter password I set in debugging options window

I tried also to recovering with Chrome extension, and after that normal mode was set again. Then I went back to development mode, did the same steps above. Getting the same result.

2. You should reach a "Developer Console" prompt, where the last line of text ends with localhost login:. Enter "root" and hit return.