Yes. As stated in the Instructions, you can use the Liberty system on as many of the cancelable categories of debts as you wish, without limit. If you need to keep at least one credit card still working, then don’t cancel that. Obviously the cards on which you apply the Liberty cancellation system will have their accounts closed and the cards will no longer work.
So, for example, let’s say you have three Visas, two Master Cards, and one Discover card. Let’s imagine that you have come pretty close to maxing out all the cards except the Discover card. On your Discover card, you still have plenty of credit and wish to keep it as a reserve in case you need it. So, don’t use the Liberty system on that one. Use it on the Visas and MasterCards, and those accounts will be closed sometime in the months following the commencement of your Liberty letter-sending campaign.