I am used to previous versions of NDK builds which came in zip format. I downloaded the recent r10 version for windows which had a .exe version. The exe version is just an extractor, that I didn't know and double clicked it. It didn't ask me for the location of extraction.
Now I want to remove this version and use a zip instead. How do I find on which location it was installed/extracted?
I tried looking to the ANDROID_NDK system variable and I found my previous definition of r8 version.
The latest version extracts itself inside the current working directory. So if you launched it from the explorer, that's the same directory as your .exe.
You should find an android-ndk-rXXX folder there. Otherwise that means it wasn't extracted.
It's always better to use the latest NDK, there are many bug fixes and improvements with each releases... You can open the .exe as an archive with 7zip, and extract it somewhere else if you need, or launch the .exe from a terminal set where you want to have it extracted.