Any suggestions on how to uh get rid of it?
If it were me, I'd stand in a room someplace and announce yourself loudly and clearly with intent to attract it's attention. Wherever it "feels"
like it is, face it head on. Odds are good you'll succeed, and probably be intensely aware of a change in the room.
From that point, I'd explain that I lived there, that it was my space, and command it to leave. It might take some time, but if you consistently
deliver the same message, insistently and forcefully, it's likely to work.
ask if they could go away
By asking you imply that "no" is an acceptable answer.
Be confident, be bold, show no fear
Yes. Absolutely critical. Your emotions will show just as clearly as your words. Being afraid while issuing a command is almost an invitation to
resist and fight you. That's not what you want. This thing probably doesn't need to sleep like you do.
don't worry they're perfectly harmless
One that's perfectly harmless does not mean that all others are.
do you think a gun would work
The point is to help instill a certain emotional state within you. If a gun will do that for you, that's fine. But if you use a gun, use it knowing
what you're using it for. As skyblueff0 points out, the gun isn't going to hurt the thing.
peacefully ask the spirit/being to stop slamming the door.
That's an option too. But understand that if you choose this route you would be accepting it's continued presence in your house. "Please stop
slamming the door" implies "I'm ok with co-habiting with you. Just make it comfortable for me, and you can live here with me."
Which is fine, if that's what you want. Don't choose this route if it's not what you want.
Also, if there are other people living here with you, I highly encourage you to talk to them about this as well. What you see might not be the same
things that they see. A predator preys on the weakest of the bunch, not the strongest. If you have children in the house, absolutely talk to them and
ask if scary things are happening to them. Also, if you command it to leave while your roomates are inviting it to stay, you're not likely to be as