Remove road, wheel cover is held on with a small nut and bolt at the back of the disc, and held at the top underneath the wheel stop lock bolt.
Make sure that you tighten the lock stop bolt back to it's original position.
There is a slight recess in the cover, that slides into the bracket where the small nut and bolt fit. Make sure that you slot it fully in or the cover will rub on the disc.
Once you have the wheel off each one should take no more than 15mins.
They just stop the road muck and stones from under the car rotting the discs and getting stuck in the brakes.But if you look on paddocks web site FTC4908 Front Brake Disc Mudshield - RH they do replacement back plates cheep.