Noise Insulation Tray? How Do I remove it?

[HumZilla]

Hi guys and gals, I'm new to this forum and would really appreciate any help you can give me. I posted this before but no one replied. I'm sorry if I have done something wrong but I'm new to this place.

I want to change the oil on my Mum's MK4 Polo 1.6 Automatic.

However I'm stuck at the first hurdle. I need to remove the noise insulation tray but dont know how. I can see some round circles and have tried to push them but they are too stiff. How do I undo the fasteners?