hedwards: It is possible for them to do that, people make that request from time to time.

Legally though, as long as GOG had a license to sell a license of the game at the time that the sale was made, then there's nothing that the rightsholder can do to force the game's removal.

The only exceptions I've heard were when it turned out that all the rightsholders hadn't signed off on the plan because there was somebody that wasn't known to have rights related to the product.