I bought a subscription on Skype using my credit card. I wanted to use it only for one month, but to my surprise they charged me at the end of subscription period (that's why they call it "subscription", duh :)
So I now wanted to get my card details off of Skype so that they cannot charge me in the next cycle. Looked simple.
Go to https://secure.skype.com/account/ then to "Payment Settings" then to "Payment methods" and cancel the card.
The problem was, my card was attached to my subscription, and Skype wanted me to cancel my subscription before it would allow me to delete the card details. The problem with that was that I was afraid that my current subscription's balance minutes would vanish if I did that. Maybe I was worrying too much, but I did not want to take a chance.
So I went to the subscription settings, and changed my payment method from my credit card to "Skype Credit". And voila, I can now delete my credit card from Skype.
I have put in a reminder for myself that at the end of current subscription period, I should go and cancel the subscription, so that it doesn't eat into my Skype Credit (if I ever did buy that).