Hi, you can replace SSD, install any m.2 nvme ssd, adding or replace RAM anything you can do. As long as you do not replace your motherboard. Windows 10 license key was bound with your motherboard hardware ID.

Just get prepare at least a 8GB USB drive, then copy the Windows 10 installer with Rufus. Then boot into the USB drive Windows installation, delete all partition, recreate new, format it then install Windows 10. That's it. If the Windows installer ask you to insert license key, you just select "I do not have any license key" to skip this option. It doesn't matter because your motherboard already registered with Windows 10 license.