Q.how do I get rid of feverfew?
Feverfew has taken over our entire landscape.

Feverfew can be invasive once it takes hold. It can be uprooted easily by hand but I do not know how practical that is in your situation - how large a landscape are we talking? You can also deadhead the feverfew blooms at the end of the summer as they fade (and deadhead any secondary blossoms that may crop up in the fall) to prevent it from self-seeding.
For more information on feverfew, please visit the following link:
https://www.gardeningknowhow.com/edible/herbs/feverfew/growing-feverfew-herb.htm