I filed a support ticket with R* to have then remove my gifted money, but since then I've picked up another $4 billion. At this point, I told them they could reset my money to $0 but I don't think anything will ever come of it. Time to just start buying tanks and chradders.
Truthfully, I've been harassing the hell out of freeroam since I got the money. Its a different spin on the game than what I was playing before. Oddly, while I still like missions, races, DMs, etc, the random freeroam warfare amuses me. I laugh a lot more playing it. There are a lot more of those tense situations where it's you vs them, and then you both get blown up by a tank. I'm not worried about vehicle costs, death costs, or ammo costs.
One night, while on foot, I started picking on a tanker and his little buddy that was baiting people into coming close enough. I think my final kill count against the two of them was slightly in my favor, which I thought was good against the two of them with me on foot. Took about an hour and a half and laughed the whole time. Then, last night, I started a war with a God mode player. He kept wondering why I was the only one able to kill him. Pro tip: it appears God mode isn't 100% God mode. If you empty a mag into their head, you can watch their life drop. As soon as you miss or have to reload though, it immediately shoots back to full. You need a big enough magazine and a whole string of head shots but eventually their life will hit 0. At least that is what was happening with this guy.
TL/DR: I gave up trying to get rid of the money and enjoy the freedom its given me. I enjoy the game MORE now.