The easiest way to get the skin off of sweet potatoes is to first cook the sweet potatoes before peeling the skin.
Cooking the sweet potatoes will allow the skin to easily slide off once the sweet potato is cooled down.
You can cook the sweet potatoes by steaming, boiling or even baking the sweet potatoes.
Then after the sweet potatoes are cooked and cooled down, you can cut off the ends of the sweet potatoes and make a slit down the center and then gently peel or squeeze the skin off the sweet potato.
For raw sweet potatoes you can get the skin off the raw sweet potatoes by using a paring knife or vegetable peeler and take off the ends first to make peeling of the sweet potato easier.
Bake, steam or boil the whole sweet potatoes until they are tender.
Then let the sweet potatoes cool down until they are easy to handle, but still warm.
Next cut off both ends of the sweet potatoes and make a lengthwise slit down the skin of the sweet potato and then gently peel or squeeze the skin of the sweet potato off with your fingers.