Delete a database with a command and how exp from O10g to OXE

Question

hi all much thanks for read the post, i followed:
NewB Question about, database, create/ delete/ show databases....
but i havent installed oracle10g (utility: DBCA) because in my new laptop with windowsvista, cant install, then i try install oracle XE on my WindowsVista Box, by moment all its ok, i try exp on Oracle10g Pc:
c:\exp UFIERROS/pass owner=UFIERROS file=FIERROS.DMP
exported!
then in pc with Oracle XE i try:
c:\imp userid=system file=FIERROSXY.DMP log=imp.log fromuser=UFIERROS touser=UFIERROS
the first time say errors (not captured), by error i type again:
c:\imp userid=system file=FIERROSXY.DMP log=imp.log fromuser=UFIERROS touser=UFIERROS
and now say:
importación realizada en el juego de caracteres WE8MSWIN1252 y el juego de caracteres NCHAR AL16UTF16
el servidor de importación utiliza el juego de caracteres AL32UTF8 (posible conversión de juego de caracteres)
. importando objetos de UFIERROS en UFIERROS
IMP-00015: la siguiente sentencia ha fallado porque el objeto ya existe:
"CREATE SEQUENCE "FIERROS_S" MINVALUE 1 MAXVALUE 999999999999999999999999999"
" INCREMENT BY 1 START WITH 110325 CACHE 20 NOORDER NOCYCLE"
IMP-00015: la siguiente sentencia ha fallado porque el objeto ya existe:
"CREATE SEQUENCE "PASE_MAESTRO_S" MINVALUE 1 MAXVALUE 9999999999999999999999"
so so same errors the file have mmm about 100 lines of warnings/errors
then the first question is:
1) if havent DBCA (or how access it), how erase my database, for try again imp..
2) How import my data from oracle10g to oracleXE?
thanks

Answer 1

i do:
C:\temp>sqlplus /nolog
SQL*Plus: Release 10.2.0.1.0 - Production on Sßb Feb 24 03:10:26 2007
Copyright (c) 1982, 2005, Oracle. All rights reserved.
SQL> conn / as sysdba
Conectado.
SQL> drop user UFIERROS;
drop user UFIERROS
ERROR en lÝnea 1:
ORA-01922: se debe especificar CASCADE para borrar UFIERROS
SQL> drop user UFIERROS CASCADE;
Usuario borrado.
SQL> create user UFIERROS identified by linuxx;
Usuario creado.
deleted and recreated, but, how use the data pump?
thanks