You should yank them and plant new ones. They grow so quickly, you won't miss them for very long. You might want to keep some of the older ones around just for the bees, though.

Keep your next crop deadheaded of all flower heads for as long as you can. Flowering saps the energy out of your plants and the foliage won't be as flavorful. Once the days start to get shorter and shorter in the late summer, however, it's almost impossible to keep them from going to seed! That's when the bees can have all they want of mine.

Let the bees have them for awhile longer.... just in case it gets cold again. It's too early to plant new basil anyway.

I'd leave them in right up until you want to plant something else there. If possible chose something unrelated and plant your new basil elsewhere as because of pest and disease increase and nutrient depletion, it's best not to grow the same plants continually in one place.