SSH

Key management

Change/remove passphrase from key

ssh-keygen -p -f <keyfile>

This will then prompt for the old passphrase and the new password (which can be left blank to have no passphrase).

This can also be done without prompt with the following one liner:

ssh-keygen -p -f <keyfile> -P <old-passphrase> -N <new-passphrase>

To remove the passphrase, simply use an empty passphrase: -N ''. Beware that when executing commands they will typically be logged in the shell history file in plain text.