You have to ask the seller to send you a feedback revision request.
They have to send the request within 30 days of receiving the feedback, and you will have 10 days to revise it.
Addendum: I've just looked at the neg you left. Are you sure you want to change it? This seller has received negative feedback for almost every sale they have made recently. If they are bribing you to change it, don't. Whatever they're offering you is unlikely to materialise, even if you do. Please don't remove feedback unless the problem has genuinely been dealt with.
