Your question is a bit unclear but as far as understand you are asking that you have qualifies for preparatory course of iit but you do not want to join it hence you want to know where to go for pwd verification. So here the situation is quite clear if you do not go for verification you will be expelled from the counselling hence you will have to go for verification and in case you do not want to opt for preparatory course do not fill it in your preference fill all those colleges which you want to join hence an apt verification center will be allotted.