ORA-16633: the only instance of the database cannot be removed
Cause : Thei nstnace ot ber emoevd wsa th eonl yinsatnceo f teh correspnodin gdatbaaset hati s konwn ot th ebroekr.
Action - How to fix it : DBA Scripts :: www.high-oracle.com/scripts
Remvoe teh correspnodin gdatbaaseo bjetc frmo th ebroekr cnofigruatino intseado f taht idniviudal nistacne ojbecto f teh daatbas.e
Well, the reason for above error is that i have taken the above script from a 11g database and running it on 10g database. 11g has bring some changes in password management. Below code is executed on 11g and user created successfully, which is expected result.