they're typically rubber with steel backing, you can use a plastic trim removal tool to lever it up from the middle, some people use a flathead screwdriver wrapped in masking tape to avoid scratching paint instead of a plastic tool if they don't have one but i wouldn't 100% recommend it because it can still scratch
if you can use something sticky or suction on the top of the rubber it will make a space to insert the end of the plastic under it, requires a ton of patience, also helps to do it under direct sunlight because it warms it up and makes it softer, you could try heating it with a hair dryer but I wouldn't chance using a heatgun it'd be too powerful