Ok I see.
What you need to do in the following order, I made the step 2 more precise:
1. First save somewhere safe your Solr index, the Solr config files, and use the admin ui to backup your MCF configs.
2. Type the command dpkg -P and delete the folder /opt/datafari (rm -rf /opt/datafari)
3. Third, install your Datafari 4.3
4. Last, push back your saved data (Solr index, Solr config and MCF configs)
Regards,
Cedric