If you have a private key for your SSH login with a passphrase attached and you need to remove the password you can use this:
openssl rsa -in private_key_with_pass_phrase -out private_key_without_pass_phrase
WARNING: a passphrase is an added layer of security in case you loose control of your private key. Think carefully about removing the password.
Common reasons for removing a passphrase are when you want to automate a login. You may be better off setting up a new user with heavily restricted access permissions.