AddRAM said:
A bit confusing, because your screen shot shows you are using the AU 1607
Specifically, the screenshot shows 'Windows 10 Enterprise 2016 LTSB' which is in support until October 13, 2026 and still gets updates. Although it is '1607' that is not the same thing as the Anniversary Update. That is 'Windows 10, version 1607' for which support ended on April 10, 2018 for Home and Pro, and on April 9, 2019 for Enterprise and Education.

As @techfixer2020 already has a supported version of 1607 it's not clear what they hope to achieve by installing an unsupported one. Anyway, I don't think it is possible to downgrade a LTSB to an RTM edition.

Edit: upgrade from LTSB/LTSC to Enterprise is possible.

Microsoft said:
You can upgrade from Windows 10 LTSC to Windows 10 semi-annual channel, provided that you upgrade to the same or a newer build version. For example, Windows 10 Enterprise 2016 LTSB can be upgraded to Windows 10 Enterprise version 1607 or later. Upgrade is supported using the in-place upgrade process (using Windows setup). You will need to use the Product Key switch if you want to keep your apps. If you don't use the switch the option 'Keep personal files and apps' will be grayed out.