I don’t need my item anymore

No problem. You can simply return your item if you are still within 30 days of receiving it. Did you buy the item in June,July of August? Then you can return it till the end of september! How does that work? Go to My Studystore, find your order and go to 'Return'. All items shown here can still be returned. Create a return order (make sure that your name and bank account number are entered correctly), print the return slip and send it along with the items to the address on the return slip. Unfortunately, returning something is not free, you'll have to take care of the shipping costs.