root 

useradd user1
passwd user1

su  -  user1


user1 - not a sudo user

useradd testuser1

[user1@server ~]$ useradd testuser1
-bash: /usr/sbin/useradd: Permission denied

su  -  root


/etc/sudoers

change permission to Read and write

remove comment from 96 and 99


Log out and log in again


userdel user1

useradd -g wheel user1

passwd user1

123
123



[root@server ~]# su - user1
[user1@server ~]$  sudo whoami
root



[user1@server ~]$ sudo useradd testuser1
[user1@server ~]$ sudo passwd  testuser1