I’m not sure where to start; Why doesn’t apt update work or why can’t I do-release-upgrade?

This is what I see when I ssh in:

Welcome to Ubuntu 19.04 (GNU/Linux 5.0.0-38-generic x86_64)

 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/advantage

  System information as of Tue May  5 01:17:40 UTC 2020

  System load:  0.51               Processes:           184
  Usage of /:   66.5% of 96.75GB   Users logged in:     1
  Memory usage: 50%                IP address for ens3: 167.71.164.222
  Swap usage:   0%

3 updates can be installed immediately.
0 of these updates are security updates.

Your Ubuntu release is not supported anymore.
For upgrade information, please visit:
http://www.ubuntu.com/releaseendoflife

New release '19.10' available.
Run 'do-release-upgrade' to upgrade to it.


Last login: Tue May  5 01:16:28 2020 from 75.40.90.27

First, let’s try to upgrade everything:

root@songsearch-gd-4vcpu-16gb-nyc3-01:~# apt update
Hit:1 https://artifacts.elastic.co/packages/7.x/apt stable InRelease
Ign:2 http://security.ubuntu.com/ubuntu disco-security InRelease
Err:3 http://security.ubuntu.com/ubuntu disco-security Release
  404  Not Found [IP: 91.189.91.38 80]
Hit:4 https://repos.insights.digitalocean.com/apt/do-agent main InRelease
Hit:5 https://dl.yarnpkg.com/debian stable InRelease
Ign:6 http://mirrors.digitalocean.com/ubuntu disco InRelease
Ign:7 https://apt.datadoghq.com stable InRelease
Hit:8 https://apt.datadoghq.com stable Release
Ign:9 http://mirrors.digitalocean.com/ubuntu disco-updates InRelease
Ign:10 http://mirrors.digitalocean.com/ubuntu disco-backports InRelease
Hit:11 http://ppa.launchpad.net/certbot/certbot/ubuntu disco InRelease
Err:12 http://mirrors.digitalocean.com/ubuntu disco Release
  404  Not Found [IP: 104.24.116.209 80]
Err:13 http://mirrors.digitalocean.com/ubuntu disco-updates Release
  404  Not Found [IP: 104.24.116.209 80]
Err:14 http://mirrors.digitalocean.com/ubuntu disco-backports Release
  404  Not Found [IP: 104.24.116.209 80]
Hit:15 https://packages.amplify.nginx.com/ubuntu disco InRelease
Ign:17 https://dl.packager.io/srv/deb/pghero/pghero/master/ubuntu 18.04 InRelease
Get:18 https://dl.packager.io/srv/deb/pghero/pghero/master/ubuntu 18.04 Release [1221 B]
Reading package lists... Done
E: The repository 'http://security.ubuntu.com/ubuntu disco-security Release' no longer has 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.
E: The repository 'http://mirrors.digitalocean.com/ubuntu disco Release' no longer has 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.
E: The repository 'http://mirrors.digitalocean.com/ubuntu disco-updates Release' no longer has 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.
E: The repository 'http://mirrors.digitalocean.com/ubuntu disco-backports Release' no longer has 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.

Ubuntu 19.04 isn’t even on this chart: https://ubuntu.com/about/release-cycle

Ubuntu 19.10 is there so let’s I’d like to upgrade to that first. But how???
What do I need to do to “unbreak” apt update?