sudo apt update will not update

Hello I'm cliff
I am using Ubuntu 20.o4.1 LTS
trying to update using the terminal, this is the result.
some thing is not right but what?
Thanks in advance for help.

sudo apt update
Ign:1 cdrom://Ubuntu 18.04 LTS _Bionic Beaver_ - Release amd64 (20180426) bionic InRelease
Err:2 cdrom://Ubuntu 18.04 LTS _Bionic Beaver_ - Release amd64 (20180426) bionic Release
Please use apt-cdrom to make this CD-ROM recognized by APT. apt-get update cannot be used to add new CD-ROMs
Hit:3 http://us.archive.ubuntu.com/ubuntu focal InRelease
Hit:4 http://dl.google.com/linux/chrome/deb stable InRelease
Hit:5 http://us.archive.ubuntu.com/ubuntu focal-updates InRelease
Get:6 http://security.ubuntu.com/ubuntu focal-security InRelease [107 kB]
Get:7 http://us.archive.ubuntu.com/ubuntu focal-backports InRelease [98.3 kB]
Hit:8 http://archive.canonical.com/ubuntu bionic InRelease
Reading package lists... Done
E: The repository 'cdrom://Ubuntu 18.04 LTS _Bionic Beaver_ - Release amd64 (20180426) bionic Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.