There are a number of ways to "move" it out of that location.
The simple way, cut & paste/drag & drop is not one of them, however. Unless you know how to rework the Registry it simply isn't going to work.
And even if you are familiar with the Registry, it's still not the best way by any means.The "best" way would be to uninstall, and re-install, FSX. That may not be the answer that you're looking for, though.
For what it's worth, I'll harp on this again - BUY AN SSD DRIVE FOR YOUR FLIGHT SIM!
Too much money? Nope -
a 240-256GBSD can be had for as little as $52.Also, you DO NOT need the fastest SSD, even the lower end SSD drives will be faster than the majority of hard drives.
A smooth flight sim experience is more than having the fastest CPU & graphics card.A simulator is like any other program in that it takes an operating system to tell it how to do what it does.
By putting your flight sim on ANY other physical drive, you'll gain some smoothness.
What happens with a single drive is that when you start FSX, the OS starts reading the FSX files, stops reading, starts writing, stops writing, starts reading, stops reading, starts writing, and on and on and on. All on that one drive.
BTW - That's an over simplification, there's a lot more reading & writing that I left out.
But pretty much any computer that you use today will be able to read off both drives
at the same time.
NOW, you are going to get a smoother experience.But don't start day dreaming about how fast your system will be, other problems
(like viruses) can slow you down too.
But this is a very good place to start.
And if you get an SSD instead of a spinning hard drive all of that flight sim reading is going to go a lot faster.