Windows 10. Is it possible to make a painless transition from UEFI to Legacy?

Question

BIOS

Hello!
Windows 10 was installed and configured on the computer. Specific software refused to work in such conditions, the developer was instructed to install a system without UEFI. The software is tied to the computer configuration and works directly with the hard drive. I'm too lazy to reinstall the system. The knowledge that I gleaned from Google directly indicates that if I just change UEFI to Legacy, the system will stop booting. As a result, questions arose:

1. Is it possible to painlessly change UEFI to Legacy?
   
2. Is it possible to somehow disable UEFI protection in the operating system itself so that specific software can work directly with the hardware?
   
3. Are there other ways to solve the problem without reinstalling Windows?
   

Answer 1

My experience is small, but positive - once I succeeded. I did this:
1. With the help of Acronis DD, I deleted a small hidden active (ie boot) partition of 100...300 MB in size and attached the freed space to the nearest large one.
2. With the help of the same Acronis DD made the partition containing Windows active.
3. Of course, I disabled UEFI in the BIOS.
4. It's an old thing, I hardly remember it, but it seems that the fourth point was also needed: if after that there were problems when loading the OS, then you need to restart from any LiveDVD / LiveUSB tool-recovery tool containing a universal set of 2k10 utilities, open the section in this set " Boot Recovery" and using the utilities available there (and there are a dozen of them) repair the bootloader on the system partition.
It is not at all guaranteed that all of the above will go smoothly, so just in case, still be prepared to reinstall the OS. However, there is no problem with the "ten" (unlike the previous ones) - it does not need to be activated, it itself.

Answer 2

Is it possible to painlessly change UEFI to Legacy?

Almost always possible.
Specific software also works through efi and bios. I'll correct you, efi is not exactly protection, it's a replacement for bios. Efi allows the system to use devices through universal APIs, which simplifies the situation with finding drivers.
You will definitely need to reinstall. And find firewood in advance.