How to fade the purple from using Gentian violet in my hair?

usingMy friend just tried to use Gentian violet to try remove the yellowness from bleaching her hair but used half the bottle and now she has purple hair. Does anyone know how to get the purple out quickly.
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my friend ended up using anti dandruf shampoo. It fades it quicker.
How to fade the purple from using Gentian violet in my hair?
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