use a user that doesn't have a private key in their .ssh folder, because it's trying to use your key since it found one in the default place. i would advise you disable password authentication though, and get your friend to make his own key pair and give you the public copy to put in his users home folder. allowing password logins is inferior to always using asymetric ciphers like keypairs are.

Thanks but this is just an experimental server. Convenience is more important. In any case I can reset the root password or just blow away the server.

In any case, I found the solution. When setting up the server on Digital Ocean. The form for selecting the keys is quite misleading and cost me a couple of hours.

• Don't select any of the keys you might have created and DON'T select "Login". (Even if you select just login, it actually seems to create a default ssh key and you cannot login without it. In this case you won't get an email. I was doing this and then resetting the password but it wont work)
• Then when you create the server, you will get an email with the password
• Login and change the default password