It is almost certainly NOT legal to sell them, assuming that the fobs came with the car when you bought it (e.g. were not additional ones you paid for  out of pocket). In that case, they really are "part" of the car and should have gone back with it, the same as you could not take out and resell the spare tire that went with the car. While as practical matter, no one may notice, care, or take action about them, if these were the remote entry fobs that came with the car, they are not your property once the car is respossessed; if you sell them, you will be selling someone else's property, which is a form of theft (probably the type known as "conversion").