Honestly, I'll go against the grain and say pull them. Why?? Because it is mid August right now and you probably have time for one more crop before the cold weather comes. If the peppers stay on the plant, you won't get near as many new flowers in the next couple of weeks. If you pick the peppers, that will encourage new flower growth.
Let the next (and last) crop of the year stay on the plant until red.
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putting them in a paper bag with a banana will get them to ripen.