Using root user is not recommended. To allow users to behave like root you can add them to the sudoers group. For CentOS, this group is called wheel. Strange, isn’t it? Why not sudo? Well, it’s wheel and that’s it.
To add the user to the sudoers group (as root)
usermod -aG wheel username
If it doesn’t work yet, edit the /etc/sudoers file (as root) using visudo
Uncomment this line (there should be two similar lines for wheel, make sure to uncomment this one and not the other one). Remove the # if it is there (do not remove the %)
%wheel ALL=(ALL) ALL
You can sudo now!