So, there are things you can do…
First would be to go to confession since a spiritual contract with Satan is a sin against divine justice. Also confess any other sins that you have committed. Next you can pray the following…
I reject any dedication, consecration, vow, pact, promise, contract or blood contract, covenant or blood covenant, to Satan of myself, my heart, spirit, soul and body, mind, memory, imagination, intellect, will, dreams, inner thoughts, sublime thoughts, touch, taste, smell, sight, hearing, stomach, blood, healthy bacteria, immune system, nervous system, and all other internal processes in the name of the Father and of the Son and of the Holy Spirit. Amen.
I consecrate myself and my heart, my spirit, soul, body, mind, memory and imagination, intellect, will, dreams, thoughts, subliminal thoughts, touch, taste, smell, sight, hearing, stomach, blood, healthy bacteria, immune system, nervous system, and all other internal processes to the Sacred Heart of Jesus and the Immaculate Heart of Mary in the name of the Father, and of the Son, and of the Holy Spirit. Amen.
Jesus Christ, I ask thee to bind all evil spirits associated with any and all evil curses, pacts, contracts, spells, seals, hexes, vexes, triggers, trances, vows, demonic blessings, or any other demonic bondage sent against me or any of my loved ones and family members, any of our possessions, and I ask thee to bind all evil spirits separately and individually to the foot of Your Holy Cross and break all seals in the name of the Father, and the Son, and the Holy Spirit. Amen. (Pray this three times)
Following confession and these prayers you must develope a habit of daily prayer and live in the state of grace, avoiding sin and the near occasion of sin, that is things that lead you to sin.
Also, the priest you choose as your confessor may refer you to seek therapy to address the areas of your life that lead you to seek a contract with Satan. Pax Christi!