You can control displaying the Favorites menu on the Start menu, by manually checking or uncheck the Display Favorites box at Start / Settings / Taskbar & Start Menu / Advanced.

To manage it via the registry, set the data value of the StartMenuFavorites value name, a REG_DWORD data type, to 0 (NOT displayed) or 1 (Displayed) at HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced.