If you are going to do this at home, then the best thing to do is apply a soap cap to try to pull the color/dye out of your hair and bring it back to blonde.
If you have some color developer at home, put some in a bottle, mix a strong shampoo with it, (not a shampoo and conditioner in one), type. Thoroughly apply it to your hair, let it sit for 20 minutes, then wash it out. You may have to do this several times to pull the color out.
If you do not have any developer then use dishwashing liquid straight on the hair.
Once you get the color up to a decent shade, then condition your hair, but do not condition until the color is up to an acceptable shade.
If you have some color developer at home, put some in a bottle, mix a strong shampoo with it, (not a shampoo and conditioner in one), type. Thoroughly apply it to your hair, let it sit for 20 minutes, then wash it out. You may have to do this several times to pull the color out.
If you do not have any developer then use dishwashing liquid straight on the hair.
Once you get the color up to a decent shade, then condition your hair, but do not condition until the color is up to an acceptable shade.