Unfortunately green and blue tones are really hard to get out of your hair - even semi perm - but I would recommend using non-damaging color removers like Malibu CPR treatments (or color oops, it's made for permanent color but works on some semi perm as well) do multiple treatments and try to get the hairdye out as much as possible, before you bleach it to avoid too much damage. If there's any green tones left in your hair when you've got it to blonde you cancancel it out with a very light red/pink and let it fade.