Generally, potato skins have something in them that is not good for chickens. (I don't know exactly what it is.) So, I wouldn't give it to them.....Throw them in the garden though, or the compost, to decompose! Good for the soil.
sweet potatos are not technically potatos...they are actually in the morning glory family I believe. however, I hear that morning glories are also toxic for chickens? Sorry, I do not know the answer to this one. Maybe someone who does will pop in soon. I will tell you that I have caught my chickens in my compost pile eatting them though...they have been fine so far.
Chickens are scavengers. They can and do eat just about anything. That said, sweet potato sprouts and green white potato skins do contain a compound that is toxic to livestock. Whether or not it would hurt chickens is anybody's guess.
As long as the peels are not sprouted they are fine.