formaldehyde strong odor neutralization
Ammonia water, AKA ammonium hydroxide ($\ce{NH4OH}$), reacts with formaldehyde to form hexamine, a comparatively innocuous solid (though it is flammable when dry).

Safer might be Neutralization of Formaldehyde Gas by Ammonium Bicarbonate and Ammonium Carbonate, which would greatly reduce the flammability of the product.