You don’t need to reset the computer. As you say, you don’t want to lose all the Windows and Dell updates.   I can think of some ways to do this. Here is one:  Assuming that the Windows license came with the laptop, its activation is tied to the motherboard. So, it will remain. All you need to do is remove the association with your Microsoft Account, and then your wife can login with her Microsoft Account. .  First, if there are applications you no longer wish to leave on that computer, you could uninstall them now.  Also, backup your user files and licence keys for any applications that you plan to uninstall and may want to reinstall elsewhere   You can login here and remove that device from your Microsoft Account:: [URL]  Once you have disassociated your account with that laptop, your user files, settings, etc. will not be accessible. At that point, your wife can login with her Microsoft Account. Then, she should access the Store app and download an app. After some time, the laptop will become added to her Microsoft Account.  If she doesn’t want to use a Microsoft Account (some of us don’t, for privacy reasons), she can creat a Windows local account. 
My 18 month old XPS 15 with Windows 10 Home is running perfectly with all Windows and Dell updates applied.  I am going to give this XPS to my wife, and I want to reset it so that she can log on with her own Windows/MS account and then install her own applications.  We don't want any of my information, applications or data to remain on the XPS.  In other words, we can a fresh start for my wife.  I do NOT want to reinstall Windows from the factory image because I have installed so many updates since the XPS was brand new. Do I do Settings > Recovery > Reset?  Will that remove my user info, my apps and data, thus allowing my wife to start with a "clean slate" and log on with her own Microsoft account? Thanks very much for any advice.  (I don't want to screw this up!) John
How to Reset XPS 15 -- not reinstall Windows