Colour strippers can lighten your hair and remove almost all the colour to give you a fresh palette to work with. Before using the stripper, you must know how to prepare your hair or the results won't be satisfying.
Use a deep moisturising conditioner on your hair for at least a week before you strip the colour. Colour stripping can leave hair dry and brittle. Hot oil treatments can also moisturise and lighten your hair.
Use a colour repair product to remove the colour from your hair.
Apply the colour stripper. Follow the directions exactly on the box of the product you chose. You can mix colour strippers with developer or water. Mixing with developer will effectively remove the colour but it is much more damaging. Try mixing the colour stripper with water to control the damage.
Consider applying another hair colour product after using the stripper. These products often leave hair with a brassy tone that you may not like. Apply a moisturising conditioner plus a moisturising shampoo to help repair your hair after stripping.
Visit a hairdresser if you are uncomfortable with stripping your hair or if the stripping isn't effective.
If you are trying to remove black dye, visit a professional.
A hair colour professional can use a toner to help neutralise unwanted colours after a colour stripping process.
Never use bleach on your hair to remove or lighten colour. Some old home remedies include mixing bleach with shampoo, but this is never a good idea.