How to remove the packages causing GPG error at once [duplicate]

So there are two PPA causing GPG warning during sudo apt update

W: GPG error: bionic InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 4FE13824E3FFC656
E: The repository ' bionic InRelease' is not signed.
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.
W: GPG error: stable InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 4773BD5E130D1D45
E: The repository ' stable InRelease' is not signed.
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.

I want to remove these PPA from my system how to do that at once?

grep -r 'repository.spotify.com ' /etc/apt

Ouput

/etc/apt/sources.list.d/spotify.list:deb stable non-free
grep -r 'brave-browser-apt-release.s3.brave.com' /etc/apt

Output

/etc/apt/sources.list.d/brave-browser-release-bionic.list:deb [arch=amd64] bionic main
/etc/apt/sources.list.d/brave-browser-release-bionic.list.save:deb [arch=amd64] bionic main

2 Answers

Reinstall the programs, but remove corresponding files in /etc/apt/sources.list.d/. In case of Brave, see if there is any corresponding file with the command

ls /etc/apt/sources.list.d/brave-browser-*.list

before, remove it

sudo rm /etc/apt/sources.list.d/brave-browser-*.list

You can edit the (PPA) repo file directly, and delete the entry(s) that you want to remove:

sudo nano /etc/apt/sources.list

Or use the add-apt-repository command, with the -r switch to remove:

sudo add-apt-repository -r ppa:<repo name>

"repo name" - The apt repository source line to add. This is one of:

1. a complete apt line in quotes,
2. a repo url and areas in quotes (areas defaults to 'main'),
3. a PPA shortcut,
4. a distro component.

Examples:

apt-add-repository 'deb stable myrepo'
apt-add-repository ' myrepo'
apt-add-repository ' free non-free'
apt-add-repository
apt-add-repository ppa:user/repository
apt-add-repository multiverse

Then update the repo lists:

sudo apt update

To delete corresponding repo keys (although yours are missing, so not required):

:> sudo apt-key list # To list all the keys
/etc/apt/trusted.gpg.d/ubuntu-repo-archive.gpg
------------------------------------------------------
pub rsa4096 2018-01-01 [SC]
F6EC B376 2474 EDA9 D21B 7022 8719 20D1 991B C93C
uid [ unknown] Ubuntu Archive Automatic Signing Key
:> sudo apt-key del "991BC93C" # Specify the key with full code, or just last 8 bytes
:> sudo apt update # Update repos