Rear wheel arch liner nuts (removal)

[Busboy]

Hi folks

I'm hoping there is a guru reading this that can guide me as to how to remove the rear wheel arch liner nuts on my tourer, on all the fixings the nut is just turning on its shaft and I can't see any way to stop this happening as it just seems that the nuts are seized, they look like plastic nuts but I'm thinking that they may be push fit, but no amount of tugging will remove them, is there a special way to remove them? Any tips gratefully received!