Clearing, not exorcism
Banishing just means removing what doesn't belong — stale energy, a lingering mood, the residue of an argument — so the space is clean before you build in it. It is the most useful ritual a beginner can learn, because everything else works better after it.
A plain one
Open a window. Take salt or just your hand, move through the room's edges once, deliberately, saying — out loud — what is leaving: this is not mine, it does not stay. Finish at the window and mean the ending. Clean space, clear intent, room to work. That's all it is, and it's enough.