How to Disable Root SSH Access on CentOS 7

First, create an alternate user instead of using the default "root"

useradd doneill

Second, set a password for this user

passwd doneill 

Third, give sudo permission for this user. For that go this file

visudo

Add permission to your user  like this. Here the user name is doneill

Now check whether you can run the sudo command with username as doneill 

1.  su doneill
2.  sudo ls

If things work good, continue

Now prevent SSH login as root user.

vi  /etc/ssh/sshd_config

Search for "Permit" word

to

Now restart your ssh service by below command

service sshd restart

Thats it.

Now please check what you have done is working fine. Don't logout now, first make sure everything is working fine.

type 

ssh doneill@your systemip

and give the password and check if the user login works fine.