If any one is trying to harm you especially a non muslim you can do this and with few days he will stop or disappear from the area.
Surah Inam ayet no 45.
Read it non stop for few days and then see how it works.
If you did it for wrong reasons it will work opposite. Will harm you instead. Be careful.
This is a Jalali Ayet. Do not smoke and do not eat onions or garlic. No smell should come from mouth and you must be in wudu at all times if possible. You can read it without wudu but you must be clean physically.