Any way to go back to windows 10 RTM (build 10240)?

[poots1101]

So on my SP3 i've had windows 8, windows 8.1, installed the tech preview of win10....and stayed a fast ring insider through RTM / Build 10240 and now on 10532. I'm having a bunch of small issues that are adding up to be a pain and wouldn't mind going back to 10240. I apparently deleted the windows.old folder because I cannot roll back to a previous build. I downloaded and created a win10 bootable USB drive via Microsoft's site, but when I booted from USB it asked for a windows product key. I have no idea where that would be, and which one I should type in. I did not make a recovery drive when I was on 10240. Am i screwed? and if the only answer is to flash back to 8.1....i'll probably just tough it out.

 

[Jack Neill]

anyway to skip the key part and move on with the install? Since your 8.1 was legit your copy of 10240 should activate without a key after the install