In the event that you sense a negative Spirit in your presence at any time, I would suggest to be saying a loving, kind, warm, heartfelt blessing to them something like: "I bless you and wish you the most loving kindness that God's People In Heaven can share with you. I wish you love, blessings, and forgiveness that you are here in my home uninvited. You are welcome to be blessed by all of God's Eternal Friends in Spirit who will be summoned after I conclude this prayer."
Then say a prayer to invite God's Holy Order of the Living Oneness of Saints and Ascended Masters to come to your home and anoint and bless it. State also: "I pray to God to deliver this lost Soul into your Loving Hands Dear Lord, and to take him into your Heart and bless this Spirit here". (I think by the time you have concluded your warm, loving, forgiving and blessings of him/her in that first prayer, the negative Spirit would be realizing that there is totally no negative reaction about to happen by you.
Negative Spirits WANT to elicit a fearful reaction so that they can siphon off this negative reaction to their presence much like a kind of food to them. Fear is an energy, and they use fear like a kind of food source to strengthen them while they roam the Earth. So don't ever give what a negative Spirit wants, see what I'm saying here? Be peaceful and loving while you say both prayers, as that will show entirely throughout your whole Auric Field, too, which is important! You can't be saying these prayers and be feeling fearful, you must be peaceful and loving in your Feelings while you are saying these prayers. Love neutralizes fear. Love Conquers fear that way. Love is stronger than fear.