There is no such thing as a clean install, if you have Windows 10. It's dirty!
I read several web sites about this. It's going to get harder and harder to protect personal information from Microsoft, Google, Apple, ...
Thankfully, I have never used a Microsoft account for any Windows OS account. I don't have any other cloud-based account either. Bought the PC with Windows 10 Pro, which made disabling Cortana a lot easier. Installed Open Shell (formerly Classic Shell) for more of a Windows 7 look & feel.
As someone else commented on, there wasn't much in the way of excessive software installed by Dell. Primarily the McAfee virus scanner subscription that I didn't want. Easy enough to remove. There are several Dell-based applications installed I am not sure whether to delete or keep.
In the past, when I performed re-installs right after a purchase, I used to avoid the Dell applications. Of course, that meant them being unable to help me if something ever went wrong, but I was either fortunate or knowledgeable enough to where I have never needed their help in almost 12 years of purchasing their PCs (Win XP first, then Win 7 before going to Win 10).