You can use the suisidewinder method. Go to a station in a system next to the one where you got the bounty. Buy a basic Sidewinder. Jump into the system where you got the bounty and use the system map to find a station that's owned by the faction that gave you the bounty.. Go to the station. When you drop out there, line yourself up with the axis of rotation about 6km out so that you're directly in line with the slot. Put 4 pips to engines and do a single boost, then fly at full throttle until you're quite close. You can reduce your speed as you go through. If you deploy your landing gear in the slot, it will slow you down inside in case you're still going too fast. Land, then take off again and fly out of the station. Hang around outside the slot until the feds scan you and blow you up. You will re-spawn back in the station with a new SW and no bounties, so you can go and get your ship, sell the SW and carry on.
key steps:
1. You must land at the station first
2. You mustn't get scanned on the way in, else they'll blow you up and you'll keep the bounty.
3. You must get scanned after you take off to reactivate the bounty, then you can blow yourself up if you want.