This is a debian related question Rocio, not a PostgreSQL one.
Check this site for further information:
http://www.debian.org/doc/manuals/apt-howto/ch-apt-get.en.html
gb.-
2008/12/9 rocio mejia <chiocjava(at)yahoo(dot)es>:
> how to unistall postgres8.3 from debian?
>
>