Does anyone know if you should be able to remove the headrest?, because I can't. I can only get it to its top position. This is a bit unfortunate as the backrest of the childseat I just bought cant be pulled up higher than the lowest setting (child seat is supposed to be compatible). Its ok for now because its the right height, but when my son grows I'll need to move it up, and if I can't take off the headrest, then the childseat back isnt flush with the back seat of the car as instructed.  thanks