The top thin strip will just pull off, then as Len said 8 screws along the bottom of the plastic trim to remove then these just slide apart to remove. Then there is another thin strip which is bonded to the car, if you are replacing the trim then you can leave this. There is a chance there will be rust under the plastic as the trim holds the water, depends how long they have been damaged. I completely removed mine and was very lucky that the sills were immaculate underneath.