Clean the database from non-spam mails?

[Johannes Klug]

Hello list,

I'd like to remove all non-spam emails from my database.
I trained bogofilter only with about 200 ham emails, now my ham-box is about 
700.
With separated wordlists, I could just delete goodlist.db, and retrain all.
If I retrained with all messages now, the first 200 would be in the db 
twice ...
Is there a way to remove all hams from the db?

Btw., why did you decide to use only one file?

Greets,

Johannes