How to get a wrench into this location to remove this nut?

Remove the valve motor (and housing), then you have access to the fitting.

Possibly you won't need to remove the valve itself, and the noise comes from the motor.

One way to do this would be to get an offset open end wrench similar to the one pictured below.

Flare Nut Wrenches. With handles, or "crowfoot" to be used with a ratchet (and extension if you need to get behind/beyond something.)

Turn off the water, relieve pressure on the system, and cut a 1 foot section out of that poorly located pipe to the right of the value (and curse quietly about they person that installed it). replace the valve. Now take the piece of pipe you removed, clean up and deburr all 4 ends, and sweat it in using 2 new copper couplings. Trying to do this any other way is going to be pure frustration, and you may end up breaking something in the process (so you'll be better off if you break it ahead of time on your own terms...).

It does look like a case of cruel & unusual plumbing, but you might be able to get to it with a basin wrench

These come in various sizes [& qualities] but they can usually grab anything they can reach.
It's difficult to tell from your photo whether this would be able to grab the bottom nut, but the top one should be relatively easy.