You will need to remove most of red first, try 10 vol lightener, you don’t need to remove all of it unless you want to be a level 8 or lighter , then ensure you mix some of the A series in with the colour, goldwell ash colours are green based(unlike most colour lines whichever are blue) but if you’re going down to a level 6 or lower, you could get away with just listening the intensity o the red and then putting the base over the topHi guys. I have goldwell topic R (very red) on the ends of my hair how would be the best way to remove the red so I can go over with a Base colour.