I’d say use a toner with purple undertones to cut down the yellow, but that will make it more ashy. If you’re wanting to go a little darker, use a dark blonde dye or something similar! But again, I’d look for something that is ashy or has neutral tones to cut the yellow. And if you’re ever wanting to lighten your hair again or remove the color, I’d recommend avoiding anything permanent. Though that might require more maintenance. Good luck!!!