Frozen indefinitely is as good as cancelled.Frozen is different from cancellation
When you is US govt, yes you can.you can't confiscate someone's assets because you don't want to pay.
Declare CPC as someone doing crime against humanity and act.
You still don't get it. People buy US bonds because they are safest way to hold value while retaining liquidity. That does not stop US from freezing bonds held by a terrorist organization indefinitely.There is inherited trust when you enter into any contract, once this trust is broken nobody will enter into contract with you anymore, even rogue nations can't do what you are asking US to do.
And indeed rouge nation cann't do it. Because their own bonds are junk.