If they are dying or rotting or sheltering slugs you can cut them off. If not leave them be. Ants will get up the stems even if you remove the leaves.

Agree with Floral that ants are not an issue. If the leaves are healthy, let them be. Watch out for squash bugs though; they like to hide under leaves which touch the ground. I'm still finding a few on my squash plants in mid Wisconsin. You want to find & kill the first adults before they lay eggs, or you will suddenly find scores of gray nymphs feeding on your plants.