Best time: Waning Moon.
Have a roaring fire going. Then go outside and pick up two handfuls of dry vervain leaves. [You can place these outside in advance if needed]. As you pick them up, shout out the name of the one you wish to be rid of. Turn and go into the house [or cross to the fire if outside] and fling the leaves into the fire with the words:
"Here is my pain
Take it and soar
Depart from me now
And offend me no more."
Do this for three nights in a row. You will hear no more from the unwanted one.