Jesus Said & these signs shall follow them that believe in my name, They shall cast out devils. Mark 16:17

Having therefore these Promises, Dearly beloved, Let us Cleanse ourselves from all filthiness of the Flesh and Spirit, Perfecting holiness in the Fear of GOD. 2 Corinthians 7:1

These Scriptures point out two things. First, the basic requirement for casting out Demons is being a true Believer of Jesus Christ. However, Never for get that you cannot be a Believer without also being an Obeyer.

"If ye love me, Keep my commandments.... He that hath my commandments and keepeth them, he it is that loveth me; and he that loveth me shall be loved of my Father, and i will love him, and will manifest myself in him" Matthew 7:21

THERE IS NO SUBSTITUTE FOR OBEDIENCE.
If you think you believe in and are serving Jesus but are not Obeying his commands as given in the bible, then you are lying to yourself. Your are not a believer unless you are also an Obeyer.

Second we are to "cleanse ourselves" From all Filthiness. I cannot think of a better Description of demons than "Filth" We are responsible to take up the Power and authority Given to us through Jesus and cast out Demons out of our own lives.

(JESUS SAID) Behold i Give to the the power to tread on serpents and scorpions, and over all the power of the enemy, and nothing shall by any means hurt you. not withstanding in this rejoice not, that the spirits are subject unto you: but rather rejoice because your names are written in Heaven. Luke 10:19-20

JESUS HAS GIVEN US THE POWER AND AUTHORITY OVER SATAN AND HIS DEMONS, BUT IT IS UP TO US TO USE THAT POWER AND AUTHORITY TO DEAL WITH THE DEMONS.

Submit yourselves therefore to GOD. Resisit the devil and he will flee from you
James 4:7

Unfortunately, usually only the second half of this verse is quoted. I cannot emphasize enough the necessity of the first half. If we are not submitted to the Lord and Obeying his Commands, than We cannot Hope to have any power OVER DEMONS.
Few people are willing to get involved in the area of DELIVERANCE, and many that do are misled into all sorts of ERROR and strange DOCTRINES. Many people are in a situation where they have no one to help them except the LORD. I want you to understand that you can take up the power and authority in the name of JESUS CHRIST and kick the demons out of yourself.

Draw near to GOD and he will DRAW NEAR TO YOU. Cleanse your hands, ye sinners and purify your hearts, Ye double minded. JAMES 4:8

EXAMINE YOUR LIVES. WHAT DOORWAYS YOU HAVE OPENED IN THE PAST ?? HAVE YOU CLOSED THEM ??? HAVE YOU CLOSED THE SINS DOORWAYS AND COMMANDED THE DEMONS TO LEAVE THAT CAME INTO YOU THEN ??? IF NOT, YOU HAD BETTER DO SO.