Different types of oil and hot water are cleaners that can help to remove a sticker. Light oils such as vegetable oil, mineral oil or baby oil can all help.
To use the oil for removing a sticker, apply a thin coat of it over the surface of the sticker and around the edges. Let it sit overnight. In he morning, start removing it by lifting one corner and gently pulling it away. Another good option is to use hot water. This works for smaller items that can be submerged in hot water, such as a vase or glass jar.