How to Stop Windows 10 from Upgrading to Windows 11

1. Pause Windows Updates

Pause Windows updates by going to Windows Update settings and selecting the Pause setting.
Two problems: you do not receive any security updates during the pause, and you will need to remember to go back into Update settings and continue pausing the updates.

2. Windows 10 Home Edition, Limit Updates to the current version

Open regedit.
I never recommend editing the registy unless you are comfortable doing so, and are willing to suffer the consequences if something goes wrong,

• Navigate to HKLM\\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate.
  (If WindowsUpdate does not exist create a New>Key and name it WindowsUpdate.)
• In WindowsUpdate open TargetReleaseVersion, change the Value data to 1, and click OK.
  (If TargetReleaseVersion does not exist create a New>DWORD, name it TargetReleaseVersion, give it a Value data of 1 and click OK.)
• In WindowsUpdate open TargetReleaseVersionInfo and assign it a Value data or 21H1 or 21H2. These are the current Windows 10 versions. Your Windows version may differ and you will need to use the appropriate version value.
  (If TargetReleaseVersionInfo does not exist create a New>String, name it TargetReleaseVersionInfo and use the appropriate Value data for your version of windows 10.)
• Restart your computer.

3. Windows 10 Pro, Enterprise, or Education Editions, Limit Updates to the current version

Open gpedit.msc

• Navigate to Local Computer Policy > Computer Configuation > Administrative Templates > Windows Components > Windows Update > Windows Update for Business
• Open Select the target Feature Update Version, select Enable, and under Options in the Target Version for Feature Updates enter 21H1 or 21H2 (the current version of Windows 10).
• Use the Apply and Ok buttons to close the Group Policy Editor.
• Restart your computer.

4. Stop Any and All Windows Updates

Open regedit.
I never recommend editing the registy unless you are comfortable doing so, and are willing to suffer the consequences if something goes wrong,

• Navigate to HKLM\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate
• Create a New>DWORD named AU
• Create NoAutoUpdate with a Value data of 1 in AU
• Restart Windows
• After rebooting your computer open services.msc, scroll down to Windows Update and select Disable.
• Restart your computer and you will no longer receive automatic updates.