spamassassin management by file deletion

I use a domain managed by HOSTROUTE, which has installed spamassassin as a mail filter.  My filespace is limited to 10MB, of which some 7.7MB are currently devoted to spamassassin.  Thus, I need to prune this quickly to maintain service.

As I do not maintain the system, I cannot manage spamassassin in the usual ways.  Instead, I think that I am limited to deleting files and altering the user_prefs file.  

The following files are present in my .spamassassin directory:

auto-whitelist, bayes_journal, bayes_seen, bayes_toks, users_prefs

As I have been unable to find documentation covering a situation like this, I would very much appreciate any insights that you could offer.

Thank you,

Colin