Hi, you only need to have a drill that is slightly larger than the hole in the middle of the rivet, and then just drill lightly until the head comes off. When all the heads are off the plate will easily come off, then you can just tap the remaining bits out with a small hammer, or pull them with pliers.
When getting a pop riveter just make sure it comes with a good selection of rivets as the ones you will need are a large size - about 4mm or so with a large head. Probably best if you measure as I don't have exact figures...
