black blue to just blue!

What sort of dye did you use? If it was a direct dye you just need to fade it, it should fade to a blue. if it was a permanent type of dye you will need to use a colour remover to get the black out. You will only need to re-bleach if your base isn't light enough, you need at least a light ginger to get a navy blue, and a blonde base for a bright blue.

I probably should've mentioned that it was just a blue black rinse on blonde hair. I just used adore rinse

Thats good, just shampoo it with dandruff or clarifying shampoo, it will fade bluer. You can soak the extensions overnight. Then you can put your chosen blue over the top.

OMG! Thanks so much you're life saver  😀 😀 😀 😀 *thx*

Just for future reference, anything labeled blue black is actually black, not blue. It's just that it's a cold, blue based black rather than a warm brown based black 🙂