18.10 - Cannot update Ubuntu18.10

I am studying Unix and installed Ubuntu
but cannot update and I cannot solve, plz help me...

Problem

cannot update ubuntu18.10 by Err

What I did for solve

I know the artful does something wrong
Searching some questions like this,
but I cannot find which line should be changed at all

deb http://archive.ubuntu.com/ubuntu artful main restricted$

      6 # deb-src http://jp.archive.ubuntu.com/ubuntu/ artful main restricted$
      7 $
      8 ## Major bug fix updates produced after the final release of the$
      9 ## distribution.$
     10 deb http://archive.ubuntu.com/ubuntu artful-updates main restricted$
     11 # deb-src http://jp.archive.ubuntu.com/ubuntu/ artful-updates main restricted$
     12 $
     13 ## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu$
     14 ## team. Also, please note that software in universe WILL NOT receive any$
     15 ## review or updates from the Ubuntu security team.$

     16 deb http://archive.ubuntu.com/ubuntu artful universe$
     17 # deb-src http://jp.archive.ubuntu.com/ubuntu/ artful universe$
     18 deb http://archive.ubuntu.com/ubuntu artful-updates universe$
     19 # deb-src http://jp.archive.ubuntu.com/ubuntu/ artful-updates universe$

(Cannot update - PPAs do not have release files)

could you explain me?

ERR MSG

E: The repository 'http://archive.ubuntu.com/ubuntu artful Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.

E: The repository 'http://archive.ubuntu.com/ubuntu artful Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.