If it is growing among other plants then weed killer spray can’t be used.  Pull as much as you can and then cover the area with cardboard or a couple of layers of brown paper (leaf bags cut open).  Cover that with cedar mulch of the mulch of your preference.  In the flowerbeds, I use cedar mulch…in the vegetable garden I use straw to cover the paper.  The paper cut the plants under it off from sunlight and they die.