So my questions to you are.... HOW does your friend know that this is a demon? Can he see it? Hear it? Or he is like one of the others posters down there who believe that ALL ghosts are demons in disguise? Because that notion is seriously mistaken. Another question--stop for a moment, ignore your fear and ask yourself WHY you're afraid. And be honest. Think about how YOU feel, not what other people are telling you. Do you actually feel threatened? Or are you afraid just because stuff is moving? Because you don't know exactly what it is? My house is filled with angels. Nothing negative can get into my house anymore. It's been sealed up tight. But my dog will NOT stay in the room with me. And she will NOT enter my bedroom closet anymore (she used to sleep in there). What is she afraid of? She's sensing something different. There's something around me she doesn't understand and so she's afraid of it.
Getting rid of it. I agree with prayer. Prayer adds light and light chases off things. You can also ask Archangel Michael for protection. How you ask doesn't matter. Then tell it to go. Tell it that you wish it no harm, but it cannot stay. Then ask Michael to escort it off your property. And try to stop being afraid of it. Michael tells me that you have only to believe you are safe in order for it to be so. By allowing it to make you afraid, you are giving it power over you. Take your power back and refuse to be afraid.
good luck.