It helps to be prepared so just twist the old clips 90 degrees and they will practically fall out . I found a broken moulded piece on the back of my wheel arch which i repaired with this stuff
The paint shop who did all my panels a couple of years ago obviously didn't find it as easy as me to remove them , or they just didn't care

and i also found this on removal
Attacked with a stanley knife i reckon , luckily the mrs has a black car and a touch up pen . Also while the inner arch is revealed i can see some flaking paint and the very first stages of rust so wire brush and Fertan are out to be followed with acid etch primer and a very heavy coat of oil based paint applied with a brush as i hope never to see behind the outer arch again
Not sure what to do about the mudflap it does have a drain but my exhaust runs directly behind the flap so anything that gets in there is going to dry very quickly and stay there , might drill a hole to stick the hose in if i can find a cap or a bung to keep it tidy .
The white stuff you see in the second pic is unibond silicone remover comes in a tube same as silicone got it from B&Q and its good stuff .