Well I hate to be the bearer of bad news, but I don't think the MS Society will let you "drop out". You can pay your minimum donation and not ride, but if you don't pay the minimum donation, I believe they prohibit you from riding in any future events. Your best bet is probably to do a "gray" transfer, where somebody else pays you the entry fee, then raises funds in your name to meet the minimum donation. They pick up your packet, sign their own name on the waiver, and ride with your number. You can call them and try to do it, but don't be surprised if they say no. They were pretty adamant about it during the signup period.