how to create user that have same permission as root in CentOS 7?
You cannot create another user with the same permissions as root. Root is a system user with special privileges. The privileges of root come from the user ID 0, not from a flag on the account or from the name “root” (that's just a convention, but a universally followed convention, so if you use a different name you'll break a lot of software and sysadmins).
You can have as many users with administrative privileges as you want. They won't be called root or have user ID 0, they're just normal accounts with the privilege to execute commands as root. The most common way to give an account administrative privileges is to configure sudo to allow them to run commands as root. Such accounts are called “sudoers”. Then, to run a command that requires administrative privileges, you run
sudo commandname argument….
useradd -u 0 --non-unique yourrootuser
You also might want to add it to root group and specify any other switches to create a user you want. User id equal to 0 is most important to achieve your goal.
usermod -aG wheel <username>
This will add your user into group
wheel which have same permissions as root.