Start with wax or clay bar. If that doesn't work, step up to something a little more abrasive like Meguiars Scratch X. Use several applications. Next work your way up through buffing compounds, starting with the least abrasive. I recommend doing this all by hand. If you're not good with a buffer you can actually burn your clear coat, even if you use a random orbital buffer. Last resort would be wet sanding with fine grit sandpaper, then buff the scuffed area to a shine with some buffing compound followed up with wax.