“Dissipate the powers of darkness that may be in this room and protect me tonight …”
1 – From the Liturgy of the Hours
This simple, beautiful and powerful prayer is part of the Completas, that is, the Prayers of the Night in the Liturgy of the Hours, and although it is prayed on specific days within the set of prayers to which it traditionally belongs, it can also be prayed at will in any time and place where you want:
Come, O LORD, this house, and turn away the snares of the enemy;
May your holy angels dwell there to keep us in peace,
and may your blessing be with us always.Through Christ our Lord.
May the Lord Almighty grant us a quiet night
, and at the end of his life a holy death.Amen.

2 – From a priest against all evil
This prayer was composed by Fr. Edward Looney , an American priest who, when traveling, always carries with him a bottle of holy water to sprinkle on the houses and hotel rooms where he is staying, asking God to dissipate all evil. As he sprinkles the holy water through the room, he does this prayer:
Almighty God, I beg you:
send your angels to be with me in this place
and protect me from all assault of the evil one.
Forgive all evil that has been committed in this room
and grant the grace of conversion to those who offended you.Dissipate the powers of darkness that may be in this room
and protect me tonight,
as well as all who sleep in this place
from now on.Jesus I trust in you!

Aen