My son has this and I spoke to a hairdresser who said to use oil (olive or coconut) in their hair and brush it out or use a nit comb but when you go to shampoo the hair add the shampoo first before any water because it will separate the oil better xx
We had it come back. On a hair wash day, put loads of coconut oil on a brush it, loads of flakes came off that way and then extra in the shower. Repeated a few times. I use a silicone brush, so it's not too harsh