You can peel the potatoes if you want to peel them.
However there's no need to peel potatoes before cooking them or eating them as the potato peel is edible and also contains nutrients.
When you peel the potato and get rid of the potato peel you also get rid of extra nutrients from the potato and when you eat the potato peel along with the potato you get the best health benefits from the potato.
Potatoes with the potato peel are more nutritious than the potatoes without the peel.
Some people prefer to peel the potatoes and throw the potato skin away but other people including myself prefer to leave the potato peel on and cook them that way.
I've cooked potatoes for mashed potatoes with the potato peel on them as well as fries with the potato peel and the mashed potatoes and fries have always turned out just fine.
So if you want the most nutrition from potatoes I would recommend leaving the potato peel on the potato.