Can someone post all information necessary to know to be able to cancel a credit card without hurting their credit score?
It's your lucky day. It's all already posted right here on the forums. It may take some digging but the info is all here.
I'll give you a quick tip though - when cancelling your card move over the credit without losing it to get another card approved.
Also, you score shouldn't drop that much even if you DO close a card.