After washing your hair with egg yolk you can use regular shampoo to wash the egg yolk and egg smell out of your hair.
Sometimes you may need to wash your hair a few more times to get the egg and egg smell fully out of your hair.
You can also wash your hair out using Chamomile tea or wash your hair out using some Apple Cider Vinegar which is also great for your hair as well.
But washing your hair out using regular shampoo after washing your hair with egg yolk will work just fine.