Presumably, to decrease the money supply, the mechanism must be the same but in reverse: selling treasuries and private assets back into the market for cash and

Presumably, to decrease the money supply, the mechanism must be the same but in reverse: selling treasuries and private assets back into the market for cash and then eliminating its existence. If the securities don't sell for much more than it was bought, accounting for fractional reserve banking, the money supply increase is effectively permanent. So if we take in the permanence of the increased money supply, can we really say we are still in a bubble if the value of the dollar against securities is simply lower?