If you are not happy with your runner beans, pull them out. They are just taking up space and pulling valuable nutrients out of the ground. Clean up the bed, put down another layer of compost and plant cool weather crops. Most leafy greens & root vegetables would do well.

Try to leave the roots of the beans in the ground though, because they will have made nodules of nitrogen which will benefit the ground next year. Its too late for root veg in the UK. Suggestions in your other question.