[NAME]  - You should still have the factory image on the SSD, so you should be able to revert back to exactly way the PC shipped. Read this for details. This will have no effect on the version of BIOS that's running.  Or, you can do a clean install by download the Media Creation Tool, free at the Microsoft site and follow their instructions create a bootable USB stick to wipe the SSD and do the install. After a clean install, any drivers that Windows Update doesn't automatically install, and any software that Dell installed can be downloaded/installed from the support page for the XPS 8940.
On 12/6 I transitioned from an old XPS to the XPS 8940. I love the new machine but the transition has been a mess. In the past I always just did the whole thing manually: set up the new PC and then slowly added all my programs and files. In this transition, I used a program (LapLinkPro) and the C/D division was too small for everything to move over. So all my programs were moved over to the C along with a big folder called "Documents" into which apparently a lot of other things were added. It looks to me like there is more junk and duplication than I expected and it is mainly stored on the C drive. It has taken up half the available space on the C. I still have to add some programs because even though they appear to have transferred, they won't boot up. But they work fine when I uninstall and reinstall. Am I over thinking/worrying for no reason? I've gone in and changed storage to point to the bigger D drive to keep my C from being too full. I've run an optimizer and haven't found anything. I've been trying to get things ironed out for a week now. Some of my file permissions are messed up even though I'm an administrator and it looks like that is mainly on some of the document files that were moved by the transfer program. Should I run some other type of program to ferret out issues or just forge ahead and fix problems as I find them? Hope this isn't too vague to answer - I think I'm just looking for some guidance/reassurance/warnings from more experienced folks who have been down this path. Thanks!
XPS 8940, transitioned from old XPS and things are a mess