Always remove the head restraint and install child-restraint system (except when installing a booster seat):
Installing a child-restraint system without removing the head restraint is dangerous. The child-restraint system cannot be installed correctly which may result in death or injury to the child in a collision.
Always install the head restraint and adjust it to the appropriate position after removing the child-restraint system:
Driving with the head restraint removed is dangerous as impact to the occupant's head cannot be prevented during
emergency braking or in a collision, which could result in a serious accident, injury or death.