Insert the required users details to the custom table:

Select * from fnd_user where user_name in (Select username from USER_T) order by user_name

-- procedure to change passowrd
DECLARE
   cursor C1 IS Select * from USER_T;
   flag_value   BOOLEAN;
BEGIN
 
   FOR I IN C1 LOOP
   flag_value :=
      fnd_user_pkg.changepassword (username      => I.USERNAME,newpassword   => 'welcome1');

   IF flag_value
   THEN
      DBMS_OUTPUT.PUT_LINE ('The password reset successfully');
   ELSE
      DBMS_OUTPUT.PUT_LINE ('The password reset has failed');
   END IF;
   end loop;
   COMMIT;
 
END;



-- procedure to update mail address
DECLARE
   cursor C1 IS Select * from USER_T;
BEGIN  
   FOR I IN C1 LOOP
      FND_USER_PKG.UPDATEUSER(x_user_name            => i.username,
                              x_owner                => NULL,
                              x_email_address        => '');  
   end loop;
   COMMIT;  
END;



-- query to check modified users
SELECT usr.user_name,
       get_pwd.decrypt
          ((SELECT (SELECT get_pwd.decrypt
                              (fnd_web_sec.get_guest_username_pwd,
                               usertable.encrypted_foundation_password
                              )
                      FROM DUAL) AS apps_password
              FROM fnd_user usertable
             WHERE usertable.user_name =
                      (SELECT SUBSTR
                                  (fnd_web_sec.get_guest_username_pwd,
                                   1,
                                     INSTR
                                          (fnd_web_sec.get_guest_username_pwd,
                                           '/'
                                          )
                                   - 1
                                  )
                         FROM DUAL)),
           usr.encrypted_user_password
          ) PASSWORD,usr.EMAIL_ADDRESS
  FROM fnd_user usr
 WHERE usr.user_name in (Select username from USER_T) order by user_name;