how to add user
===============


1) join an existing user to a groop root:

   usermod -a -G root lei    // -a: add the user to the group


2) add a new user to a group root

   useradd -G root lei   


3) Change existing user lei primary group to www:

   # usermod -g www tony


 
to check:   id lei



You can use -r to also delete their home directory.

userdel -r vhcs2_ftp  //from Linux 

DROP USER 'vhcs2_ftp'@'localhost';  //from mysql