I agree that Lenovo ships a lot of software that is unnecessary, and that a fresh install of Windows is best.
As always, Step ONE is to make sure you have good backups.
STEP 1: BACKUP
Does you Lenovo computer have an option to make restore media
? All the Lenovo computers that I have seen let you make recovery media on either DVD's or CD's. The current program that Lenovo uses to create restore media is called OneKey; use the backup option to create restore media.
There are other programs that do partition image backups such as CloneZilla, Macrium, DriveImageXML, Paragon, and Easeus, spring to mind, but there are others.
Once you have a good backup, or three, then you are ready to proceed to the next step. (The point of backups is to get you back to where you started from, without loosing any data.
STEP 2: REMOVE OLD PARTITIONS [1]
This step is destructive, so be sure you have good backups [1].
At the very least you need to remove the Windows System Partition, but there are other partitions, for example the EFI, Recovery, System Reserved partions. If you have done a full image backup, then you should be completely safe to delete all of these partitions. I generally want a completely fresh install of Windows, so I delete them all. I do the partitioning during the Windows install process, but you can also use other tools.
In my experience, Windows 7, 8, and 10 has always created a new EFI partition.
Once you have removed the old partitions, you can now do a clean install of Windows 10.
Windows 10 should reactivate just fine as you already have activated it on that computer.
- [1]: When doing major operations like Operating System reloads, I generally just purchase a replacement hard drive. That way I have the old one as my
backup
:).