Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.
It is a well-known fact that jinn can take different forms such as human beings and animals, etc. An example of this is when Satan came to the unbelievers on the day of Badr (battle) in the image of Suraqah Ibn Malik . If jinn takes such forms, man can kill him, as really happened during the time of the Prophet (peace be upon him). In Sahih Muslim, there is a long Hadith (Prophet's saying) which includes: … the man took his spear and went back to see his wife standing between the two doors. Out of jealousy, he rushed to stab her with the spear. She said: 'keep your spear away from me and come in to see what forced me to get out.' He entered the house and found a huge snake coiled in the bed. He pierced it with the spear and got out of the house and planted the spear in the ground, with it twisting painfully on it. Then it was not quite clear which died first, the snake or the young man. He then said: "We came to the Prophet (peace be upon him), told him about what had happened and asked him to supplicate to Allah that He may restore his life. He (peace be upon him) said: Ask forgiveness for your companion", then said: 'Verily there are jinn in the Madinah who embraced Islam, so if you see anyone of them warn him for three days and if he appears to you (after that period) kill him for he is a devil'. Allah knows best.