Removing raw data files

Hello,

I asked this question a while ago and I didn't get an answer.
Perhaps I asked the question in a manner that wasn't clear.  I
upgraded from 8.1.3 to 8.2.3.  I left the 8.1.3 database intact in
case I had to revert to it.  The 8.2.3 database is running just fine
and I'd like to recover the space that the 8.1.3 raw data directories
are consuming.  Can I just remove the raw data files with rm -rf on
the data directory for the 8.1.3 version?  This may sound like a
silly question but the database I worked with prior to postgres was
MS SQL Server.  On that platform, you never know when something from
the last version is imbedded in the new version.

Carol