In Luke 8:2, And certain women, which had been healed of evil spirits and infirmities, Mary called Magdalene, out of whom went seven devils. . .is one of the most remarkable events.

           The Bible says specifically and emphatically that this woman had seven devils in her. Jesus cast them out and she became one of His disciples.

                  This does prove that humans can have evil spirits in them and that Jesus can cast them out.