Thank you for your reply,
You do not understand my problem. I know that Flash player is integrated with Windows 10 (I mentionned it in my request). This version is OK. My problem is with the version that is in Windows.old. When I run Microsoft update it updates the integrated version of Flash player and not the version in Windows.old.
Windows.old will not be used by your upgraded operating system. No Adobe installer will recognize it period. Your current windows system will not use or recognize it period. The only remote way is is some malware got on your machine and specifically targeted c:\windows.old\windows\system32\macromed\\flash...... That is the only remote way aside from the current version of Flash being exploited to do that ( i don't know too much on hacking and doing malicious stuff )
The windows.old directory is there in case you want to go back to your previous operating system. You could delete it, but at YOUR own risk, furthermore that windows.old will NOT be touched by windows updates; why would it it is the OLD OS!
In theory could someone write some malicious code to target it; yes.
thank you for your reply but you did not answer to my question. I already know all what you say.
I leave no security breach in my IT infrastructure so even if there is just a little chance to be attacked I want to eliminite completely the risk.
Does someone know how to do ?
Then IF you are an IT pro for a company, why don't you build an image for it ?
That is what we do, we do not upgrade machines, we build images, then deploy them; actually we build hardware independent images. That is the way to go, then you will have NO old windows lingering around.
I also think what you are asking is beyond the scope of these forums since you are dealing more of an operating system question and how to get around permissions on old files. This forum is not a windows 10 upgrade forum.