I hope they weren't glued on! That would be a first for me but these days nothing surprises me when it comes to dealer prep.
Plastic trim removal tools are useful to remove stuck on plates, and cheap on eBay / and online shops, as long as double sided tape (or pads / strips) have been used. Having just removed a set, held on by double sided tape, I lucked out and one came off with ease, leaving nothing behind but the rear left most of the tape on the vehicle. I soaked the old tape in Goo Gone and after a few minutes, used a plastic edge to remove it. It took time but I worked at it and got it all off.
The new plates were fitted using Wurth adhesive mirror tape, which I've recommended on here before, and the front was on a curves surface. I've never lost a plate on any car and that includes metal plates on curved surfaces, as well as standard acrylic plates.
