Programming and Technology

To install a package signing key you have to use the apt-key add command. For example if you want to add the Google signing key:

wget -qO- https://dl-ssl.google.com/linux/linux_signing_key.pub | sudo apt-key add -

To remove a key you first need to know its keyid. You use apt-key list for this:

sudo apt-key list
...
pub   1024D/7FAC5991 2007-03-08
uid                  Google, Inc. Linux Package Signing Key 
sub   2048g/C07CB649 2007-03-08

Once you know the keyid you delete it with this command:

sudo apt-key del 7FAC5991

Source: Askubuntu