How to get rid of demon followers?

My friends and I went to a park and we saw a lot of bad oras and ghosts. So later that night we went back to the park, and decided to make our own ouiji board with a sharpie on a cement bench. Instead of a proper triangular mover device, we used my friend's skull ring. We then asked all the normal protocal questions, like if it was safe to use this and if we should use this, and got "yes" on both answers. We then asked if we offended anyone by making this, and we got a "no." We asked then how many spirits were among us, and they said three. So we asked what one of their names were, and we got "w-i-l-l-i-a-m." We asked how old this william character was, and the ring went across the board and then stopped moving. We tried to clarify how old the spirit was, and it said it was 20 years old. We then asked if it could make a sign to prove its presence, and then my friend said something was tugging on his jacket. Then my other friend's eye turned gray. And my other friend through up this spit up stuff. I got extreme goosebumps. We then asked how it was, and it said fine. My friend was being an idiot and burning a leaf and the spirit (who admited to being a demon) said it was offending him. When we got home my friend had a strange mark on his back. I had two marks on my back, and we discovered our marks were parrellel to each other. They disappeared within 30mins. So I think they followed me back home because I've been feeling very cold, had nonstop goosebumps, feel like something is touching me, and I keep hearing scary sounds. I'm home alone, with the lights on, freaking the hell out, and I need some help to get rid of these demons following me.