How can I lighten black hair dye?

I had this problem and went to a professional hairdressing supplies shop - it’s where hairdressers buy their hair dye and hairdressing tools like scissors, clips etc. In the UK, the shop to go to is called Sally’s. I bought a product called Rusk id Elimin8 Color Corrector. It gently removes unwanted colour from hair - semi and permanent - no matter how long ago you dyed it. It has no peroxide, ammonia or bleach in it, so consider it’s stripping out the colour from your hair, it’s the gentlest product on the market. There are three bottles - step 1 and 2. You mix them together then apply it to your hair. I could see in just a few minutes that it was working, and after 20 minutes, I rinsed it off. It really got the black out, but my roots were much lighter. Then I applied the processing lotion, which made my hair really dark again. I only used half the mixture, so I did the whole process again, this time not putting any on the roots, and my hair went light orange. I then washed it out and didn’t use the processing lotion on it. I then put a semi permanent over the top and it looks healthy and vibrant and not black! I’d recommend this product, but be careful with your roots!