I would use Color Curves to remove a reddish caste. To do that, very slightly increase the colors blue and green. Make the increase in both colors at the center point of the curve. Do not adjust the end points since color fades away as you approach black or white (i.e. the curve end points). Blue and green mix to produce the color cyan. Cyan reduces the color red. So that increasing blue and green makes the color less red. However, the increases also brighten the image somewhat. To offset the increase in brightness, reduce the color red in the same place and by the same amount. I suspect that the adjustment needed will be fairly small.
You select colors by using the “Channel” in the Color Curve screen. The default is RGB, but you can also select red, green, or blue.