Sweet peas

Hello! I have just put in over 150 sweet peas all various shades and have a question. My seeds have been overwintered in the greenhouse and are really healthy. However, each seed has produced three stems. Can I trim each plant so that only one strong sweet pea remains to go up a string. I was attempting the cordon method but I have adapted that slightly. I am hopefully going to create a beautiful highly scented barrage of colour this year. Fingers crossed x