If you have Windows 10 installed and you do not want to upgrade to Windows 11, you can use this process to stop the upgrade to Windows 11.
1
Click your Start Button, then just type cmd and from the resulting list, right click Command Prompt and choose 'Run as Administrator'
Paste this command into Command Prompt and press Enter:
reg add HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate /v TargetReleaseversion /t REG_DWORD /d 1
Paste this command into Command Prompt and press Enter::
reg add HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate /v TargetReleaseversionInfo /t REG_SZ /d 22H2
Close Command Prompt
2
Open File Explorer, then navigate to C:\Windows\SoftwareDistribution\Download
Delete the contents of that folder, not the folder itself and restart (not shut down) your PC.
3
In the future if you ever want to upgrade to Windows 11, you will need to open the Registry Editor and delete the TargetReleaseversion and TargetReleaseversionInfo entries from this key (folder).
HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate