removal of the yellow safety stripes shouldn't be too difficult. Try a chisel xacto blade? I've found sucess by taken the blade end and lightly scraping the unwanted paint. To do this, hold the xacto blade edge 90 degress to the car and lightly drag it. It may take a couple of passes to remove all of it. With that being said, even if you were to make a small mistake, it could be remedied with weathering.
Just take your time..