I planted free comfrey

For some reason I thought comfrey was NA native, so I wasn’t too concerned at grabbing some free plants and root cuttings from someone local. Well it’s not, and I don’t really want to spread invasives. I have it in a pretty isolated garden bed right now, but should I:

just rip them carefully out and start fresh?

Wait till they seed and try and germinate some to see if they’re sterile

Somehow identify the strain via photos or some sort of tells?

Thanks for helping a fledgling gardener.