You can login to an SSH server without password by using public key authentication via these steps;

1. Generate an SSH key pair. Make sure to not set any passphrase for the key pair

   How to generate SSH keypair

2. Enable public key authentication in the target server

   How to disable public key authentication in SSH

3. Copy your SSH public key to the server

   How to copy SSH public key to server

You will no longer be prompted for password the next time you log in to the server.