Hiya folks!

I had a mystery squash growing in my compost, and thought I'd plant it in my little garden plot since something I planned to plant (collard greens) had the seeds disappear.

And, it turns out, the mystery plant is pumpkins! It is growing well, but, as pumpkins tend to do, it is taking over the garden. It's not too bad, as the things that are planted already are going to be harvested soon (leaf lettuce is about to bolt, and the broccoli is growing so well! first time I've done that). However, there is one plant I'd like to save from the teeming mass. Can I cut back vines without damaging the plants? Is there a special technique?

Thanks!