How to get rid of "404 Not Found" errors when doing apt-get update?

Question

ruby

Kubuntu 14.04
After installing MiniDLNA from sources, errors appeared when running apt-get update:

apt-get update output

...
Ош  http://ppa.launchpad.net trusty/main amd64 Packages                        
  404  Not Found
Ош  http://ppa.launchpad.net trusty/main i386 Packages                         
  404  Not Found
...
W: Не удалось получить http://ppa.launchpad.net/stedy6/stedy-minidna/ubuntu/dists/trusty/main/binary-amd64/Packages  404  Not Found

W: Не удалось получить http://ppa.launchpad.net/stedy6/stedy-minidna/ubuntu/dists/trusty/main/binary-i386/Packages  404  Not Found

E: Некоторые индексные файлы не скачались. Они были проигнорированы или вместо них были использованы старые версии.

Contents of the /etc/apt/sources.list file

# deb cdrom:[Kubuntu 14.04 LTS _Trusty Tahr_ - Release amd64 (20140416.1)]/ trusty main multiverse restricted universe

# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://ru.archive.ubuntu.com/ubuntu/ trusty main restricted
deb-src http://ru.archive.ubuntu.com/ubuntu/ trusty main restricted

## Major bug fix updates produced after the final release of the
## distribution.
deb http://ru.archive.ubuntu.com/ubuntu/ trusty-updates main restricted
deb-src http://ru.archive.ubuntu.com/ubuntu/ trusty-updates main restricted

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team. Also, please note that software in universe WILL NOT receive any
## review or updates from the Ubuntu security team.
deb http://ru.archive.ubuntu.com/ubuntu/ trusty universe
deb-src http://ru.archive.ubuntu.com/ubuntu/ trusty universe
deb http://ru.archive.ubuntu.com/ubuntu/ trusty-updates universe
deb-src http://ru.archive.ubuntu.com/ubuntu/ trusty-updates universe

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu 
## team, and may not be under a free licence. Please satisfy yourself as to 
## your rights to use the software. Also, please note that software in 
## multiverse WILL NOT receive any review or updates from the Ubuntu
## security team.
deb http://ru.archive.ubuntu.com/ubuntu/ trusty multiverse
deb-src http://ru.archive.ubuntu.com/ubuntu/ trusty multiverse
deb http://ru.archive.ubuntu.com/ubuntu/ trusty-updates multiverse
deb-src http://ru.archive.ubuntu.com/ubuntu/ trusty-updates multiverse

## N.B. software from this repository may not have been tested as
## extensively as that contained in the main release, although it includes
## newer versions of some applications which may provide useful features.
## Also, please note that software in backports WILL NOT receive any review
## or updates from the Ubuntu security team.
deb http://ru.archive.ubuntu.com/ubuntu/ trusty-backports main restricted universe multiverse
deb-src http://ru.archive.ubuntu.com/ubuntu/ trusty-backports main restricted universe multiverse

deb http://security.ubuntu.com/ubuntu trusty-security main restricted
deb-src http://security.ubuntu.com/ubuntu trusty-security main restricted
deb http://security.ubuntu.com/ubuntu trusty-security universe
deb-src http://security.ubuntu.com/ubuntu trusty-security universe
deb http://security.ubuntu.com/ubuntu trusty-security multiverse
deb-src http://security.ubuntu.com/ubuntu trusty-security multiverse

## Uncomment the following two lines to add software from Canonical's
## 'partner' repository.
## This software is not part of Ubuntu, but is offered by Canonical and the
## respective vendors as a service to Ubuntu users.
# deb http://archive.canonical.com/ubuntu trusty partner
# deb-src http://archive.canonical.com/ubuntu trusty partner

## Uncomment the following two lines to add software from Ubuntu's
## 'extras' repository.
## This software is not part of Ubuntu, but is offered by third-party
## developers who want to ship their latest software.
# deb http://extras.ubuntu.com/ubuntu trusty main
# deb-src http://extras.ubuntu.com/ubuntu trusty main

Because of this, I cannot install dependent libraries and Ruby through RVM.

Answer 1

look at the rep list files and remove the ones giving 404

cd /etc/apt/sources.list.d/
ls
less xxxx.list
sudo rm xxxx.list