To hide the version number of the OpenSSH server from clients, you will need to edit the /etc/ssh/sshd_config file and add the following line:
ServerKeyBits 3072
This will change the size of the server's host key, which will cause the version number to be hidden.
You will need to restart the OpenSSH server for the changes to take effect. On most systems, you can do this by running the following command:
sudo service ssh restart