Except for someone who exactly knows what drivers you are talking about, it's hard to give any help. Isn't EZ-USB a trademark of Cypress and thus the drivers from Cypress as well? What's the difference between the drivers you're mentioning?
One typical reason for what you encounter, general and not specific to Win 10 either (was the same in earlier versions) is if the driver you're trying to replace is newer than the driver you want to replace it with. I think the only way of doing that is to 1/ go to the Device manager and uninstall the corresponding device from there, 2/ manually delete the driver files (at least the .inf file, good luck finding it in the Windows directories), and finally 3/ install the other driver.
If you do 1/ but not 2/, Windows will pick the previous driver next time you plug the device in.
And, if the driver you want to replace is actually a Windows-provided driver, manually deleting it is at your own risk. It may come back at the next Windows update anyway.
Your best bet would be to find a replacement driver that is newer than the existing one.
All this, of course, is assuming that the driver you want to install indeed corresponds to the right device, refer to what Daixiwen said. So my answer is the next step after you checked that.