They really have no resale value. They are going for less than $1 per point on Ebay and most of those probably get taken by Marriott through ROFR. Sure there are some people buying them at $3-$4 per point to get them through ROFR, but that is probably a select few buyers. Right now there are way more sellers than buyers. You could try to sell them. If you find a buyer then they will be gone. Even if Marriott takes them through ROFR. You could always ask Marriott if they will take a deed back for $0, which I am sure they will do.
If you have an outstanding loan on the points, then you are kinda stuck.