First of all:
Create a simple user with ssh login:
- $ useradd -m -s /bin/bash username
- $ passwd username
Open a second shell and log the user in. Try command
to check, if your user can login as root as well.
After successful test ...
Set "PermitRootLogin no"
Reload configuration with
Open a third shell and try to login as root -> should not be possible anymore.