Run Command Prompt as an administrator (“Win” logo key + “Q” to open Search box, type”Command Prompt”, select “Run as administrator”), and copy and paste the following commands into the Command Prompt and press Enter to run one by one.

reg add “HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\WindowsUpdate\UX\Settings” /v FlightSettingsMaxPauseDays /t reg_dword /d 1000 /f

Source: https://answers.microsoft.com/en-us/windows/forum/all/how-do-i-disable-automatic-windows-10-updates/9ee64521-5236-4df4-b31f-1e9457eda600