How to remove paint odor?

Open the windows. Use a fan. Air it out. It will go away eventually.

What @lillycoyote said is the only way I know of getting rid of the smell. You should be fine so long as the windows are open. A fan will help it to dry quicker. If it really bugs you as you sleep, put a fan at the window and direct it to blow your way so you drag in fresh air from outside. It will usually go away in two days unless its an oil base paint. Then it may take a week.

It certainly is not good for you.

Ventilation is my first recommendation. Open all the windows, perhaps turn on a fan to circulate the air as @lillycoyote recommended.

That smell can hang around for more than a week (think months, maybe even years), even with really good ventilation. A charcoal air filter is another option if it is truly unbearable and you are up for the expense.

Next time, try to get them to use paints with lower to no VOCs.

It’s not going to harm your health. Open the windows for a few days.

Get some activated charcoal and set them in bowls in the middle of the rooms or better if you can get a room air purifier with activated carbon/charcoal filter media to hasten the movement of the air.

Spray water every time you go in there. The spray mist will take the smell molecules down to the floor (or something like that). Place an open box of Baking Soda in the room, it will absorb the odor.