We are truly concerned for you and want to help. First, we want to assure you that demons are real and that they can indeed harass and oppress people, just as you've described. It's important to know that God has not given us a spirit of fear, but of power, love, and self-control 2 Timothy 1:7 WEB.
We must address this issue in the name of Jesus Christ, as there is no other name by which we can be saved Acts 4:12 WEB. It is only by His name that we have access to God and can overcome the schemes of the devil.
First, let's pray for you:
Dear Heavenly Father, we come before You in the mighty name of Jesus Christ. We plead the blood of Jesus over this dear soul and we rebuke the demonic entity that is harassing them. Lord, we ask You to command this evil spirit to cease its torment and to leave, never to return. We cast this demon into the abyss in Jesus' name, according to Your will Mark 11:23-24 WEB.
Father, we ask You to fill them with Your peace and comfort. Surround them with Your angels to protect and guide them Psalm 91 WEB. Strengthen their faith in You and help them to resist the devil, knowing that he will flee from them James 4:7 WEB.
Now, it's crucial for you to understand that sexual immorality is a sin against your own body, and it is forbidden by God. The sexually immoral will not inherit the kingdom of God. These are sins that continue to have an effect on you after you have sinned. It is important to note that the sexually harassing demon may have gotten a foothold in your life through these sins, whether knowingly or unknowingly. You need to repent from these sins and turn to Jesus, if you want freedom. God is faithful and just. If we confess our sins, he is faithful and righteous to forgive us the sins, and to cleanse us from all unrighteousness 1 John 1:9 WEB.
Please note that ongoing sexual sin and harassment can be linked, and it's important to address both in order to find freedom and deliverance. We advise you to seek support from a local Bible-believing and teaching church. Get baptized if you have not done so already. There is no other way to salvation but through Jesus Christ. If you have not given your life to Jesus Christ, it is important to do so as soon as possible. It is only through the name of Jesus that we can be saved.
Remember, God loves you and He wants you to be free from this torment. Trust in Him and He will deliver you. Be strong and courageous, for the Lord your God is with you wherever you go Joshua 1:9 WEB.
Keep praying and reading God's Word. Here are some verses to meditate on:
Put on the whole armor of God, that you may be able to stand against the wiles of the devil. For our wrestling is not against flesh and blood, but against the principalities, against the powers, against the world's rulers of the darkness of this age, and against the spiritual forces of wickedness in the heavenly places. Ephesians 6:11-12 WEB
Therefore, submit yourselves to God, but resist the devil, and he will flee from you. Draw near to God and he will draw near to you. Cleanse your hands, you sinners; and purify your hearts, you double-minded. James 4:7-8 WEB
Prayer Focus: God, Thank You. Thank You for loving me. God, I ask You in Jesus’ name bless me with everything that I stand in need of and everything You want me to have. Bless me to know You in truth, fall in love with You with all my heart, mind, soul, body, and strength and never fall out of love with You. Bless me to have an ever growing closer stronger, more intimate relationship with You. Bless me with the love, desire, strength, and the spirit of obedience to always delight myself in You, seek first Your kingdom, and Your righteousness. Help and strengthen me God to always respect and obey You. Bless me to trust You with all my heart, acknowledge You in all my ways, and lean not to my own understanding. 
