I pray that your father will turn back to God so that he may be healed in body, mind and spirit. Below you can find some spiritual healing prayers against evil / occult practices. You may have difficulty getting your dad to say them for himself so you may need to say them on his behalf. I hope they help. May God's will be done, in Jesus' name, amen.
Prayer against Evil
Spirit of our God, Father, Son and Holy Spirit, Most Holy Trinity, descend upon me. Please purify me, mold me, fill me with yourself, and use me. Banish all the forces of evil from me; destroy them, vanquish them so that I can be healthy and do good deeds.
Banish from me all spells, witchcraft, black magic, demonic assignments, malefice, maledictions and the evil eye; diabolic infestations, oppressions, possessions; all that is evil and sinful; jealousy, treachery, envy; all physical, psychological, moral, spiritual and diabolical ailments; as well as all enticing spirits, deaf, dumb, blind, mute and sleeping spirits, new-age spirits, occult spirits, religious spirits, antichrist spirits, and any other spirits of death and darkness.
I command and bid all the powers who molest me—by the power of God Almighty, in the name of Jesus Christ our Savior—to leave me forever, and to be consigned into the everlasting lake of fire, that they may never again touch me or any other creature in the entire world. Amen.

Denouncing the Occult
Heavenly Father, in the name of your only begotten Son, Jesus Christ, I denounce Satan and all his works, all forms of witchcraft, the use of divination, the practice of sorcery, dealing with mediums, channeling with spirit guides, the Ouija board, astrology, Reiki, hypnosis, automatic writing, horoscopes, numerology, all types of fortune telling, palm readings, levitation, and anything else associated with the occult or Satan. I denounce all of them in the name of Jesus Christ who came in the flesh, and by the power of his cross, his blood and his resurrection, I break their hold over my life.
I confess all these sins before you and ask you to cleanse and forgive me. I ask you Lord Jesus to enter my heart and create in me the kind of person you have intended me to be. I ask you to send forth the gifts of your Holy Spirit to baptize me, just as you baptized your disciples on the day of Pentecost.
I thank you heavenly Father for strengthening my inner spirit with the power of your Holy Spirit, so that Christ may dwell in my heart. Through faith, rooted and grounded in love, may I be able to comprehend with all the saints, the breadth, length, height and depth of Christ’s love which surpasses all knowledge. Amen.
