Wiping HDD while keeping certain programmes?

[M3M3G0D]

I'm looking to sell an old iMac I bought a while ago (don't worry, this isn't an advert), and before I do so, I want to clear the Hard drive of any personal information, login informations, history etc. However, I have a few useful programmes which I would like to keep on the mac, such as eDrawings, and some very legitimate copies of Office and Solidworks, as perhaps they might assist me in selling the computer. I was wondering, is there any way of wiping the HDD while exempting those select programmes? One other issue I may have is the fact that the mac is running windows 7 through bootcamp, which is where the aforementioned programmes are, and may need updating to Windows 10 since Microsoft is cutting support for Windows 7. In that case, I'll also have to update OS without deleting those programmes. Is there a viable way of doing this? Or am I better off just wiping the bootcamp partition and installing a fresh copy of windows 10?