I have struggled with thoughts to, not exactly in the way you have but I hope I can help. If you feel satan is near you just say this, "satan I rebuke you in the name and in the blood of my Savior Jesus Christ that now you may no longer touch me and I command you to leave now in Jesus' name." As for getting rid of the thoughts, constant prayer helps. Maybe you are having guilt like I was, if so get on your knees and ask God to take away your guilt, He did it for me. It helped me to stop. Also, keeping your mind pure. Stop watching TV shows that constantly promote these things or sin in general. Instead, watch more things that focus on God. There is a program I love called The 700 Club. The first part of the show is news in the world dealing with Christianity. Some is interesting but my favorite part is next when people come and share their testimonies and they tell us about the charities and how they are converting people in China and India and Muslims and other places and how they provide homes and fresh water for people! To see the look on their faces is AMAZING! It warms your heart and strengthens your faith. Go to cbn.com and find out what channels. I watch it on ABC Family @11 p.m. but I'm on the east coast. I hope I helped some. You are in my prayers. If you have any questions please ask. I would love to help. You said you were only 14, well I'm only 16.