I had some pimples previously and i scratched and plucked it and now it has left some marks like black ones ll that go with time or permanent? i am 16 years?

Scars are hard to completely remove & although they may fade over time, they generally remain visible. But dark spots from acne are flat on the surface of your skin & they don’t indicate any long-term skin damage. Dark spots generally become lighter over time & eventually disappear. So you should be gentle with your skin & try to avoid causing any scars. I wish you well with your health!