Remove Windows Insider Program Page contains the registry files to hide the Windows Insider Program page found in Start > Settings > Update & Security. You can also manually edit the registry.

Download Remove Windows Insider Program Page and extract the two files.

Double-click 'Windows Insider Program Page - Remove.reg' or 'Windows Insider Program Page - Add.reg' (Default).

Click Yes when prompted by User Account Control.
Click Yes when prompted by Registry Editor.

Click OK when prompted by the Registry Editor.

This tweak is included as part of MajorGeeks Windows Tweaks.

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How to Enable or Disable Windows Insider Program in Windows 10

How to Enable Windows 10 Insider Program Without a Microsoft Account

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How to Enable the Windows Insider Program When Grayed Out