You're talking about the worship of "satan".
Witchcraft is not satanism.
Witchcraft is not Satanism but many types of Satanism involve witchcraft...
Witches do not even believe that satan exists.
Perhaps the majority of witches who restrict themselves to practicing only Wicca do not believe in Satan, but Wicca is only one of many Pagan religions which involve witchcraft, and only one of many religions where those who practice it consider themselves to be "witches", and thus the term "witch" is not strictly a Wiccan term. Wicca is a relatively newer religion that was influenced by much older Pagan religions.
Besides... what use would a Satanic figure be to Wiccans when they really only practice the "Light Side" of witchcraft?
Many witches do believe in Satan, and may or may not view Satan from the traditional Christian point of view. Many witches do believe in a sentient source of all "evil" which they may or may not refer to as "Satan". For some this Source is instead Lilith, or some other god such as Ahriman/ Angra Mainyu.
The witches that dare to practice the "Dark Side" of witchcraft may not even believe in a sentient source of all evil, but instead, a Natural, non sentient Force that is beyond our comprehension... perhaps the collective energy of "negative" or "evil" human emotions and practices. Or perhaps they may view that Force to be alive after all. Not as a deity, but a living current of energy intertwined with the Light in a cosmic dance.
One needn't be an adherent of Wicca, or possess a belief in a Satan, to be a witch and practice "witchcraft".