Problem: Want to login to CentOS 7 via username and password only, remove private key login.
Solution: First of all, follow this video instruction if you haven’t built the Amazon EC2 or able to connect server via private key yet.
Then inside the server terminal command line, edit /etc/ssh/sshd_config
Edit the line “PasswordAuthentication no” to (or if you can’t find the line, just add) “PasswordAuthentication yes“

restart SSH service
systemctl restart sshd.service
Don’t forget to change the password for user. For the current user,
passwd
for root,
sudo passwd