Check out this article. It has a nice walkthrough of the process.
Migrate NSX for vSphere to NSX-T
As you might know, I use a test/demo environment from my employer. In this environment, I can demo the VMware SDDC products for customers or colleagues. Since the start of the environment approx. four years ago, I had a demo around NSX for vSphere, but as you know, the product has been announced to go end of support in 2022 and there will be no more development on it.
Dennis Bray's Virtual Place 