Question about my hood

[n00b on demand]

Ok so the previous owner had the famous SVX bra on the hood of the car. The day i bought it i took the bra off and there was a line going across the hood that never came out after my initial car wash with the car. So i put the bra back on and left it but still cleaned under it every day. This weekend i took it off and noticed the car looked so much better without it. But my problem is that now this line goes across my hood....it has black gritty crap in it that comes off if you scratch it with your fingernails. The rest of the paint if flawless except for this one line going across. I was told if i use some wax it might come off...but any of you have suggestions to how i can get the gritty black dirt off without damaging the paint and suggestions on getting the line out?