Okay,
I have 7 guppies in a ten gallon with two varieties of plants, red ludwigia, and green foxtail. I want to get some cory cats, but I just had a whole bunch and I mean a bunch of rather ugly looking black snails born in my tank. I think they came in with the plants. How can I get rid of them with out damaging plants or fish? I thought about aquarium salt, but I don't know what that will do to my plants. I also thought about jungle parasite control, but again would it harm my plants.

These snails are not "mystery snails" like the ones sold in the stores, those have eggs above the water line. What you have are most likely either physids or planorbids. Now the bad news...any two or these critters can procreate and they lay eggs on EVERYTHING which makes them extremely difficult to get rid of. There are chemicals out there such as "Snail Away" that will get rid of them, but I'm personally always leery of putting chemicals in my fish. You are already pretty well stocked, so a loach may not be an option, but they are the best snail-eaters on the market aside from puffers, but most puffers would also cheerfully snack on your guppies. Clown loaches, skunk loaches, etc. work great, any botia species loach.

Would jungle parasite control get rid of them without hurting the plants or the guppies?

The parasite control MIGHT kill them, it's designed for the sort of parasites that live on the fish, but a lot of those meds will kill inverts. However, a lot of plants are sensitive to them (I'll let someone more knowledgeable in plants be more specific about which ones) and, like many meds, they can be hard on the fish. In other words, quite a bit of risk for not the best outcome.

What if I take the plants out and keep them elsewhere, and salt the aquarium? How could I treat just the plants outside the tank in another container? Would salt kill the snails in my tank if I have removed the plants?