I want to go really white blonde after putting in a violet base toner to cancel out the yellow i have what dy?

If it is really dark use a blonde dye that does not have any kind of golden or red tint to it. Example: don't use golden blonde or strawberry blonde. If it's light use just a light blonde dye. Use something that is Honey wheat, pale blonde. This way you won't come up with red hair. Unless you want that.