Removing types
- The default types are in file opt/eprints3/archives/ARCHIVEID/cfg/namedsets/eprint, edit it accordingly.
 - Edit corresponding entries in /opt/eprints3/archives/ARCHIVEID/cfg/lang/en/phrases/eprint_types.xml (It might be no harm to leave them there.)
 - Restart apache
 
Thanks for the help and hints from Ian Stuart.