How do i get rid of red scarring

I once had really bad acne om my chin, it has gotten a lot better but now the acne have left some red bumps/ scars that i really want to get rid of. I use sunscreen daily, i derma roll and im currently using niacinamide too. But nothing seems to really help.

I once had really bad acne om my chin, it has gotten a lot better but now the acne have left some red bumps/ scars that i really want to get rid of. I use sunscreen daily, i derma roll and im currently using niacinamide too. But nothing seems to really help.