Remove both wiper arms by lifting the plastic cap over the spindle and undo the nut which holds the arm onto the spindle. Do this with the arms in the parked position so you know where to position them when refitting. Pull off the spindle to panel rubber seals.
Open the hood and you will see three bolts holding the panel to the firewall, remove these and lift the front of the panel up and forward towards the rear edge of the hood, it will unhook from under the windshield and lift off. The mesh screen is just glued to the underside of the panel with some black muck.
Clean it up and re-glue with something suitable.
Reassembly is the reverse of dismantling as the books always say.
A good idea would be to put masking tape on the rear 3inches or so of the hood to avoid paint damage.
Hope this helps, Colin.