I tried this but maybe I did it wrong.Get the a Windows ISO from Microsoft
Download Windows 10
www.microsoft.com
Boot from it and it will walk you through the process of clearing the drive and re-installing Windows. Bonus, it will be completely clear of any Lenovo pre-installed things. You'll have to get any missing drivers from Lenovo support.
Went to that windows web page and started the download. It download windows 10 and then while still in windows 10 (ie I'm on thr desltop) it started to reinstall the OS.
Did all that and sure I have win10 again minus the Lenovo stuff that usual comes with.
Turned off machine did the reset button and same results as above. Still bitlocker. Cause I never got an option to nuke the drive/partition.
I liked the bios world better as I knew that stuff.