Solution 1: Possess chavi just as you possessed rano and jump of a cliff which will kill chavi.
solution 2: use all your ghost friends to kill chavi.
solution 3: with black magic make chiku a super dog and send him to attack chavi.
if you can't do this in supernatural way, then do it the human way. So here is the human solution-
solution 1: run her over with a truck or something big or may just with your car.
solution 2: take a gun and shoot her or may be knife and stab her.
solution 3: hire a hit man.
There are many more solutions. But still if can't do it you should really go to hell.
Personal advice for our beloved simi, LEAVE THIS CRAP SHOW NOW.