I want to go platinum using Paul Mitchell's HLP?

Since your hair is already colored with the reds you will have no choice but to bleach it to become blonde. HLP is a color not a bleach and color does not lift color. Only bleach lifts color. If your hair was (virgin) meaning your natural color you could use the HLP. Since you already have color in your hair you have to use bleach to lift it. Even if it is semi-permanent. When and if you do bleach it, it will lift to a blondish, pinkish color because of the red you have in it. You will have to tone it to get to your desired shade of blonde to get rid of the pink undertones. I suggest using a color remover before you do a bleach wash. Color removers are less damaging. After the color remover you will still have to bleach your hair but not as much as you would if you didn't use a color remover first. Get it done professionally though. trust me the products they use are ALOT less damaging than the over the counter crap.