The context and parallel passages (compare Deuteronomy 17:7; Leviticus 20:2) indicate that there was to be a regular judicial procedure, and that the manner of the execution was to be by stoning. In this the community was to take its part in order to show its horror at the crime, and to clear itself of complicity therein.
Related Commentaries of Deuteronomy 13:5
Deuteronomy 13:5
5 And that prophet, or that dreamer of dreams, shall be put to death; because he hath spoken to turna you away from the LORD your God, which brought you out of the land of Egypt, and redeemed you out of the house of bondage, to thrust thee out of the way which the LORD thy God commanded thee to walk in. So shalt thou put the evil away from the midst of thee.