Where is the option to deselect a debit card from the payment options menu?

Okay, so i had made a purchase wiht my Visa Debit Gift Card about a month ago. I knew my balance was low on my card (about $0.91). With that in mind and knowing the exact balance i had gone a made a purchase. Now, however, the itunes on my comupter said i had $0.51 left in my account. My ippod itunes store app said i had $0.88 left in my account. I had made the purchase on my ipod note. In seeing that amount (the $0.88) i mad my purchase. everything went thru with no errors, until later in the month. I go to update a few of my apps from the itunes computer version. when i tried to update, it said i had to confirm my payment method. So, thinking i would just choose "none" i clicked okay. Come to find out, my debit card is still attached to my account and i cannot undo this and im also in debt $1.29. Apple, you suck first off. And second, i've been reading that adding an itunes gift card will not undo this debt...furthermore i must continue to say Apple, you suck. Why can i not undo this?