Yes, cut off the branch growing from the roots, because that part of the tree isn't supposed to make branches (just roots). It's not a good variety for eating, but it's good for vigorous/healthy roots.

Leave any branch or leaves that are above the graft and growing. You can cut back the old trunk once you are sure it's dead (cut it above the new growth).

The leaves and little branches you see growing now (above the graft) will form the framework of your 'new' peach tree. They will grow and get tall, etc. Eventually, you will train them to grow the direction you like. For now, just take care of them and let them grow to feed the tree.

I'm still experimenting with and learning about fertilizer myself.

Cut the peach tree as mentioned, took another picture to let you see what it looks like now. Concerned when I cut the middle stem back, the inside looked dead. Will the middle branch die completely. And new branches above the graft union, will there branches look like the one that is dying

If the growth higher up on that main branch got killed, it'll be toast, yeah. But those do look like two nice branches already growing well above the graft. Awesome :)

Those branches (one of them) will form your new trunk, eventually. So you'll be looking at selecting one of them to be that main trunk. The other will be cut off, but that's down the road, imho. I think right now the tree needs the leaves, etc, from the 2nd branch to feed the tree. So you won't be cutting either one yet if you do what I'd do.

You'll be straightening up one of the branches (or both, if you like) once it's not quite so delicate. It will be trained to replace the main trunk, see?

But wait a while before you do that, imho, because it's also easy to snap them off! I would wait until the texture of the branch is tougher :)

I wouldn't remove any branch until winter/spring pruning next year, myself, but I do pinch them once I know they are branches I'm not going to use as the main one. I just pinch the tip off once they are maybe 9" to a foot long, and I let my chosen branch grow on taller and taller.

Others might have different philosophies about whether to pick the main trunk branch now and cut the others, though! I'm no expert, just going through this, too :) I have one tree (cherry) whose main trunk died way back last year when it was planted bareroot. Mine grew back straight up on its own, so that was nice, lol.

Thank you Meredith. You make it so much easier to understand and the steps to take one by one. As a novice that is great. Clearly understand and will follow your suggestions.. If everything continues to go right I will wait until the branch on the right gets stronger and then begin to pinch back the one on the left. Thanks again

Thank you for the compliment! I'm sure there are lurkers on this thread who will jump in if I've led you astray in any important way :) I'm sorry I can't say conclusively that my advice is the best way to go, but I'll need lots more experience under my own belt before I can know that :) It's what I'd do, so that's the best I can offer, lol!

Best of luck! I think the tree looks really good, considering. You made it happy after it was sad, so that's definitely good news. Not having to buy a new tree also means your tree's roots are older, so you saved time (a year?) by saving the tree as well.