

This is tagged as performing a downgrade and hence would call for a clean install- aka factory resetting your PC.

This is because, at that point in time, you would be on a higher version of Windows (the pre-release Dev build) and would be then trying to move over to the lower version (Beta). And once your PC starts receiving these pre-release builds, then it would be quite a challenging task in moving over to the Beta version.

But now that the Beta builds are live, Microsoft will soon start delivering prerelease (standalone developer) builds again. In the initial phase, Dev was the only build available, so whatever features it was being blessed with were the only ones tied to a specific release. On the other hand, most of the beta features are expected to make it to the end of the day.
