Wear something that can get dirty/oily or have your child just take their clothes off. 
Thoroughly comb out the live lice and nits (eggs) and dispose of them. (Mature lice are black, the young ones are gray, and the eggs are white.) Vacuum the area.

Go in the bathroom and apply the coconut oil to the whole head until it’s thoroughly coated from the scalp to the ends. Have your child put their head back and apply many drops of tea tree oil to the head but make sure it doesn’t get in the eyes or it will sting like heck! Comb the tea tree through the hair. Put on a shower cap, put a towel around the shoulders to soak up dripping oil, and have a small washcloth to wipe the face.

Watch movies or do something similarly sedentary for as long as possible. (At least four hours is recommended but longer is better. As long as they can before bed is best.) Strip the beds, wash the linens and any clothing that’s been worn within the last few days, and put other bed items that can’t be washed (pillows, stuffed animals) in a sealed bag for a few days-week. (The lice usually die within a few days without access to the host). You should also wash or cover with plastic, carseat covers, hats, and other things that touch the head on a regular basis.

In the bathroom, mix many drops of tea tree oil in a small bottle with shampoo and save for later.

Go back to the bathroom, remove the shower cap and comb out the whole head, using the lice comb. Wipe the lice and eggs on a paper towel and look to see if anything is still alive. (There shouldn’t be but if any lice survived, apply more coconut and tea tree oil for a few more hours.)

In the shower, apply the tea tree shampoo and, without getting it in their eyes, carefully shampoo your child’s head. You may need to do this twice to get the oil out.

Put clean sheets on the bed, find clean pajamas, and put your kid to bed.