so i never had any credit card info on one of my accounts..
but after logging in the other day apple tried to apply my card info from a hardware purchase...
I couldn't even download a free app without verifying my card info..
solution to remove all card info from the account:-
in iTunes log into your account
in the store menu select view my account
then select edit payment information or billing
at the top you see all the credit card select radio buttons
and at the end is option NONE
select this and you will not be able to make any pay for purchases in iTunes...
but free purchases will still work...
I hope this is helpful
Please note that you can still redeem Gift cards to make pay purchases !!