Update user username and password

For security reasons, here the procedure to update the username and the password of a user.

Here how to update the enable password.

enable
configure terminal
enable secret new-password

Here how to update the username and password of a user for a WebUI access.

enable
configure terminal
username new-username privilege 15 privilege 15 secret new-password
no username old-username

Here how to update the username and password of a classic user.

enable
configure terminal
username new-username password 0 new-password
no username old-username

After that, you can enable the password encryption and save the configuration

service password-encryption
exit
copy running-config startup-config