[E. Pluribus Unum]

They’ll find a way. The NSA knows every owner of bitcoin and their wallet key. If their wallets disappear, bitcoin disappears.

[Errant]

They may know many or even most owners of bitcoins, but they don't know the majority's wallet key. If they were devious enough to go inside their device and delete their wallet, there's always a backup for the prudent.

Heck, you can even print out the codes, hide them someplace, or commit them to memory, and delete the wallet yourself. Try doing this with anything else of value. I believe this characteristic of crypto-money is what makes it appealing to anyone living in a country with a ruthless government and controls on capital (e.g., Cyprus, US, China, and others).