Yeah, if you want to have a good result I recommend you to bleach your hair.
If you have used darker colors on your latest dyeing (brown, black, caramel) you will probably have to do a color removal, because it's pointless to try to use bleach on colored hair if you have darker hair.
But remeber that color removal is sometimes extremely
damaging for your hair, so think carefully. It's also pretty expensive on hairdresser: / After you have removed your color, it's okay to dye your hair with that egoist pink color :3
If you have lighter hair, you can try to use bleach. It's also damaging for hair, but not as much as color remover.
But since you have already colored your hair, I recommend you to do a color removal. It might be harmful to your hair, but bleach will most likely not
work on your colored hair.
I hope this helps you, but feel free to ask if you more guestions!