Cannot remove a repository that complains it has no public key
10101
How can PPAs be removed?
83924
error while trying to sudo apt-get update GPG, no sign repository
29461
Is it possible to delete an enrolled key using mokutil without the original .der file?
23303
How can I solve "Be aware that removing the lock file is not a solution and may break your system"?
154420
"Failed to download repository information" error
155404
Delete fork dependency of a GitHub repository
61948
ssh no longer allows public key authentication
93942
How to fix "Failed to download repository information" error while updating?
12054
How do I deal with "unauthenticated sources" errors in the Software Center?
149245
What to do about "the disk drive for /dev/mapper/cryptswap1 is not ready yet or not present"?
10193
Failed to download repository information due to missing CDROM
21483
no such file or directory 'authorized_keys'
134563
How do I remove a broken software source?
130650
E: The repository 'http//archive.canonical.com precise Release' is not signed
106931
How to undo sudo add-apt-repository?
80899
"no public key available" on apt-get update
144685
how to get rid of arm64 in apt