to be sure i always do a secure erase on the ssd plus installing the only windows 7 iso that i trust, which is my personal iso, also you create a new wallet with the new installation
in that way i know that i'm safe at 100%
The best free secure erase software I know of is called eraser. The first dev did a first class job of it, but then another dev took over the project and ruined it. The last good version that works well is 5.8.8, and you can download it here.
https://sourceforge.net/projects/eraser/files/Eraser%205/5.8.8/Eraser%205.8.8%20Portable.zip/downloadI recommend using it to securely erase any wallet you want to get rid of. You are responsible for your money's security if you use Bitcoin.