Complex sentence: Direct Democracy principle has been removed at party's second conference, held in Thessaloniki on Dec 7-8,2013 by a 10-20 supporters of the Sweedish pirateparty (noted that the proceedings of this conference were not published).
Split into simpler sentences: Direct Democracy principle has been removed at party's second conference, held in Thessaloniki on Dec 7-8,2013. The decision was taken by 10-20 supporters of the Swedish Piratpartiet (noted that the proceedings of this conference were not published).