With a knife.
It is not necessary to peel sweet potatoes before roasting them. The skin of sweet potatoes is edible and can become crispy when roasted, adding texture and flavor to the dish. However, some people prefer to peel sweet potatoes before roasting for a smoother texture.
No, you do not have to peel sweet potatoes before cooking them. The skin is edible and contains nutrients, but some people prefer to peel them for a smoother texture.
The potato/apple/vegetable/cucumber peeler has been invented and re-invented many times with slightly different features. The cheap one still preferred by many people in the United States with a stiff blade and metal handle has been attributed to a blacksmith named Thomas Williams sometime in the 1800s, but there does not seem to be any documentation of this.
Peeling sweet potatoes before cooking is optional. The skin is edible and contains nutrients, but some people prefer the texture of peeled sweet potatoes. It's a personal preference based on taste and recipe requirements.
Crawling
bikes
Buttons.
benches
pickaxes
Shoelaces were invented long before people bothered to keep records of such things.
Potatoes...lots of potatoes.
Before the refrigerator was invented, people used iceboxes, which were essentially big coolers with a block of ice. Even before that, food was preserved by salting, curing, smoking, drying, and canning.