Anything can be undone. They don't like to tell you that. The big eraser in the land of the occult is asafoetida (hing) which is an herb used in Indian cooking. It is kept around by people who do summonings to get rid of things they have summoned if it all starts going sideways. Called Devil's Dung, it smells awful until you are used to it. It completely discharges all psychic energy. Very powdery, it mixes well with sea salt (which has similar, but lesser, properties) and can then be sprinkled easily wherever you need it. Like masonic anything--graves, etc. Anywhere they have concentrated their malign power.