You say, "You are not welcome here." Wait a few min, and say it again, if you notice it again.
Get out!!! Get out of the house!!!
Who ya gonna call?
If it hasn't harm you ever then let it be.
You should take the opportunity to obtain replicable evidence that it really exists.
Let it be, unless it is causing dangerous problems. Unexplained Phenomena that repeats itself often enough would be subject to study Scientifically, and may lead to some new insights in Physics. There is no proof that the Phenomena are "Ghosts" or "Spirits of the dead" anyway.--Those are just superstitious explanations for unexplained Phenomena.
It depends on what it is doing. If it is disturbing you then the first course of action should be to make peace with it, tell it that it is disturbing you, and that it is welcome to stay as long as it doesn't scare you. If that doesn't work then by all means try and evict it.
Bear in mind that it was here before you, so by rights it should be you that should leave.
Take not a jot of notice of idiots like Gary. Some people dig their heels in and no amount of evidence will suffice. The law courts require a damn sight less evidence than Gary to hang people. Police witnesses or even a ufo landing in his garden will not get acceptance from people who would rather carry on looking silly than face facts that they are wrong. If you think I go at Gary a lot, it is because I can't abide a fool and his stupid comments are a waste of everyone's time. As for your question, I would let it get on with it unless you felt it was causing a nuisance. We don't know what they are and that includes everyone, so leave well alone. Some people often say they like the extra presence in their home as it is company.
Keep it! Tell everyone - you could be rich and famous! If you actually have a real ghost you'll overturn all science and physics - the existence of ghosts has NEVER been proved.