It all depends on what type of filler was injected. HA fillers are reversible, but all others are not. HA fillers can easily be dissolved by injecting hyaluronidase into the area where the filler exists. Hyaluronidase is an enzyme that breaks down the filler to bring the area back to baseline. As far as other fillers, there’s no easy or safe way to undo their effects, so, unfortunately, you’ll have to wait it out and let them naturally break down.