/item 34 CRASH

Hello i have a VERY big problem i need help.on 1 server i bought for 100$ a Rank that gives me a lot of commands. one of them is /item. i done /item 34 witch is some kinda of part of piston and my minecraft just crashed! i try to join the server but i cant i guees because of that item in my invertory.please help me im so sad right now and dont know what to do please help me i payed 100 dollars for rank and now i cant even join the server!