How can ssh access for root be disabled?

Removing SSH from /etc/inetd.conf would only affect SSH if it were managed by inetd, but SSH typically runs as a standalone persistent daemon and is not controlled by inetd.

The rlogin setting in /etc/security/user governs rlogin protocol access, which is a separate service from SSH and has no effect on SSH login behavior.

The file /etc/ssh/sshd_config is the OpenSSH server daemon configuration file. Setting PermitRootLogin to 'no' instructs sshd to reject all authentication attempts by the root account, which is the correct and universally supported mechanism for disabling root SSH access on AIX and other Unix-like systems.

ssh_config (without the 'd') is the SSH client configuration file, not the server file; additionally, RootPasswordAuthentication is not a valid directive in sshd_config.