Right, but those are fed reserve dollars. It would destroy the fed dollars. The treasury can print up notes and coinage as legal tender though
Normally paying off the debt this way would cause massive deflation, but so would not paying it off(as interest expenses grow larger than the economy) But paying off the debt 1 to 1 with treasury issued notes, off of negative refinanced interest, would keep the same monetary base and extinguish the Fed, and probably leave the government with money left over
Its literally impossible to pay off the national debt with a debt based CB currency, because as you pay off the debt with new dollars you are creating more debt. To even try to pay it off would crash the entire economy and create a massive deflation/depression.
But there is a way to fix the problem. With the negative interest rates the federal govt can now just borrow 20+ trillion new dollars at negative interest to service the old debt, and then have the treasury issue new currency 1 to 1 on the new debt. It would destroy the central bank (with the treasury taking over) and the national debt would be gone virtually overnight(at a profit no less). This is what Trump is actually doing I believe
It exists to make people dumb