CREATE USER monkey PROFILE "DEFAULT" 
	IDENTIFIED BY "d3ath!!!"
	DEFAULT TABLESPACE "TBLSPACE_USER" 
	TEMPORARY TABLESPACE "TBLSPACE_USR_TEMP" 
	ACCOUNT UNLOCK;

system>create user myuser identified by myuser;

User created.

system>grant create session, create procedure to myuser;

Grant succeeded.

myuser>create or replace function my_function
  2  return number
  3  is
  4  begin
  5    execute immediate 'create user newuser identified by newuser';
  6    return 0;
  7  end;
  8  /

Function created.

-- As MYUSER, let's try executing the function.

myuser>var rtn number
myuser>exec :rtn := my_function()
BEGIN :rtn := my_function(); END;

*
ERROR at line 1:
ORA-01031: insufficient privileges
ORA-06512: at "MYUSER.MY_FUNCTION", line 5
ORA-06512: at line 1

-- Nope, doesn't work.  Need the grant

system>grant create user to myuser;

Grant succeeded.

-- OK, now I have the grant.  Let's try again.

myuser>exec :rtn := my_function()

PL/SQL procedure successfully completed.

-- Now it works

grant create user to myuser with admin option;

select * from user_sys_privs
 where privilege = 'CREATE USER';

SQL> select * from user_sys_privs
  2   where privilege = 'CREATE USER';

no rows selected