I have a Schengen visa (business class) from one of the EU countries. It is multi-entry type valid for 18 months (90 day stay), I used this visa to visit the EU last month and it will remain valid till January 2015.
My question is can I cancel this visa? Or reduce the validity of it to 6 months only instead of 18 months? And if yes do they need a reason for it? Is it easy or hard to achieve the cancellation?