I have jack in a pulpit growing wild I want to get rid of them how do I kill them?
You can either choose a broadleaf herbicide, or boiling water. Both will kill this pretty well. I do prefer boiling water, as it will not leave the soil toxic, and will work much faster.
This summer I noticed more than ten Jack in the Pulpit flowers. I live in New England an d am wondering if they are rare.
Jack In The Pulpit's are found in the woods of many areas of much of the US.
These articles will give you more information.
https://www.fs.fed.us/wildflowers/plant-of-the-week/arisaema_triphyllum.shtml
https://www.gardeningknowhow.com/ornamental/flowers/jack-in-the-pulpit/growing-jack-in-the-pulpits.htm
What do I do to protect the sseeds until they turn red 9or will they just die on the ground?
To give them the best chance, I would bring them in and put them somewhere dry. Once they are dry, you may store them. I fear that they may rot where they are sitting, now.