Need some help/assistance from anyone.

I received my Wetokole's today and while trying to put on the bottom part, I realized I need to take the plastic piece off of the seat. Can someone tell me how to do that?? I have a 2010 cabrio. The instructions say they 'normally' come off with the simple twist of a phillips head screwdriver, but I haven't been able to find the screw as of yet.

Any advice would be much appreciated.

Thanks,
Shelley